LeetCode算法题目解答汇总(转自四火的唠叨)

比眉伴天荒 2022-07-13 06:13 182阅读 0赞

LeetCode算法题目解答汇总

本文转自[《四火的唠叨》][Link 1]

只要不是特别忙或者特别不方便，最近一直保持着每天做几道算法题的规律，到后来随着难度的增加，每天做的题目越来越少。我的初衷就是练习，因为一方面我本身算法基础并不好，再一方面是因为工作以后传统意义上所谓算法的东西接触还是太少。为了题目查找方便起见，我把之前几篇陆陆续续贴出来的我对LeetCode上面算法题的解答汇总在下面，CTRL+F就可以比较方便地找到。由于LeetCode上的题在不断更新，因此我也会不定期地更新。下面表格里面的Acceptance和Difficulty的Easy/Medium/Hard的分类都是来自LeetCode上面的数据，而Difficulty括号里面的数值和Frequency则来自[这个文档][Link 2]。另外，LeetCode数据库的那十道题（截止到目前）我[记录在这里][Link 3]。

总体来说，做LeetCode的题目收获还是很大的。而这种可以很快获得代码正确性和性能即使的反馈的方式，对算法提高也是很有帮助的。有的题目困难，主要包括两方面的原因，有的是思路比较怪异，用常规思路去解题往往时间复杂度或者空间复杂度过高，还有的则是需要考虑的情况比较复杂，case众多，很容易遗漏。

<table> 
 <thead> 
  <tr> 
   <th><a rel="nofollow">Title</a></th> 
   <th><a rel="nofollow">Acceptance</a></th> 
   <th><a rel="nofollow">Difficulty</a></th> 
   <th><a rel="nofollow">Frequency</a></th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><a rel="nofollow">Palindrome Number</a></td> 
   <td>28.8%</td> 
   <td>Easy (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">ZigZag Conversion</a></td> 
   <td>23.4%</td> 
   <td>Easy (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Valid Sudoku</a></td> 
   <td>27.6%</td> 
   <td>Easy (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Add Binary</a></td> 
   <td>25.5%</td> 
   <td>Easy (2)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Valid Parentheses</a></td> 
   <td>28.2%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Valid Palindrome</a></td> 
   <td>22.2%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Balanced Binary Tree</a></td> 
   <td>32.5%</td> 
   <td>Easy (1)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Valid Number</a></td> 
   <td>11.0%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Symmetric Tree</a></td> 
   <td>31.6%</td> 
   <td>Easy (1)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">String to Integer (atoi)</a></td> 
   <td>14.2%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Same Tree</a></td> 
   <td>41.8%</td> 
   <td>Easy (1)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Level Order Traversal</a></td> 
   <td>30.6%</td> 
   <td>Easy (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Level Order Traversal II</a></td> 
   <td>31.0%</td> 
   <td>Easy (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Roman to Integer</a></td> 
   <td>33.9%</td> 
   <td>Easy (2)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Reverse Integer</a></td> 
   <td>39.8%</td> 
   <td>Easy (2)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Nth Node From End of List</a></td> 
   <td>29.3%</td> 
   <td>Easy (2)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Element</a></td> 
   <td>33.0%</td> 
   <td>Easy (1)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Duplicates from Sorted List</a></td> 
   <td>34.7%</td> 
   <td>Easy (1)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Climbing Stairs</a></td> 
   <td>34.0%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Duplicates from Sorted Array</a></td> 
   <td>32.2%</td> 
   <td>Easy (1)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Plus One</a></td> 
   <td>31.4%</td> 
   <td>Easy (1)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Path Sum</a></td> 
   <td>30.4%</td> 
   <td>Easy (1)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Pascal's Triangle II</a></td> 
   <td>30.1%</td> 
   <td>Easy (2)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Pascal's Triangle</a></td> 
   <td>31.1%</td> 
   <td>Easy (2)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Minimum Depth of Binary Tree</a></td> 
   <td>29.4%</td> 
   <td>Easy (1)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Merge Two Sorted Lists</a></td> 
   <td>33.2%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Merge Sorted Array</a></td> 
   <td>31.8%</td> 
   <td>Easy (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Maximum Depth of Binary Tree</a></td> 
   <td>43.8%</td> 
   <td>Easy (1)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Longest Common Prefix</a></td> 
   <td>27.0%</td> 
   <td>Easy (2)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Count and Say</a></td> 
   <td>26.7%</td> 
   <td>Easy (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Length of Last Word</a></td> 
   <td>29.0%</td> 
   <td>Easy (1)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Implement strStr()</a></td> 
   <td>21.9%</td> 
   <td>Easy (4)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Divide Two Integers</a></td> 
   <td>16.6%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">3Sum</a></td> 
   <td>16.7%</td> 
   <td>Medium (3)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Evaluate Reverse Polish Notation</a></td> 
   <td>19.9%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Find Minimum in Rotated Sorted Array</a></td> 
   <td>31.7%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Word Search</a></td> 
   <td>19.8%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Word Ladder</a></td> 
   <td>18.4%</td> 
   <td>Medium (3)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Flatten Binary Tree to Linked List</a></td> 
   <td>28.2%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Gas Station</a></td> 
   <td>25.9%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Generate Parentheses</a></td> 
   <td>31.4%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Gray Code</a></td> 
   <td>32.1%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Word Break</a></td> 
   <td>21.3%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Validate Binary Search Tree</a></td> 
   <td>25.9%</td> 
   <td>Medium (3)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Insertion Sort List</a></td> 
   <td>25.3%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Integer to Roman</a></td> 
   <td>33.8%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">4Sum</a></td> 
   <td>21.4%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Jump Game</a></td> 
   <td>27.2%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Add Two Numbers</a></td> 
   <td>22.9%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Anagrams</a></td> 
   <td>23.9%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Decode Ways</a></td> 
   <td>16.2%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Letter Combinations of a Phone Number</a></td> 
   <td>26.4%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Linked List Cycle</a></td> 
   <td>35.7%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Linked List Cycle II</a></td> 
   <td>30.8%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Best Time to Buy and Sell Stock</a></td> 
   <td>31.2%</td> 
   <td>Medium (2)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Unique Paths II</a></td> 
   <td>27.9%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Longest Palindromic Substring</a></td> 
   <td>20.6%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Longest Substring Without Repeating Characters</a></td> 
   <td>22.2%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Unique Paths</a></td> 
   <td>31.7%</td> 
   <td>Medium (2)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Unique Binary Search Trees II</a></td> 
   <td>27.3%</td> 
   <td>Medium (4)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Unique Binary Search Trees</a></td> 
   <td>36.5%</td> 
   <td>Medium (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Two Sum</a></td> 
   <td>18.4%</td> 
   <td>Medium (2)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Convert Sorted List to Binary Search Tree</a></td> 
   <td>27.3%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Maximum Product Subarray</a></td> 
   <td>15.9%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Maximum Subarray</a></td> 
   <td>34.0%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Triangle</a></td> 
   <td>26.6%</td> 
   <td>Medium (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Best Time to Buy and Sell Stock II</a></td> 
   <td>36.6%</td> 
   <td>Medium (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Swap Nodes in Pairs</a></td> 
   <td>32.4%</td> 
   <td>Medium (2)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Convert Sorted Array to Binary Search Tree</a></td> 
   <td>32.9%</td> 
   <td>Medium (2)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Container With Most Water</a></td> 
   <td>31.3%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Minimum Path Sum</a></td> 
   <td>31.0%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Surrounded Regions</a></td> 
   <td>14.2%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Multiply Strings</a></td> 
   <td>20.5%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Sum Root to Leaf Numbers</a></td> 
   <td>29.7%</td> 
   <td>Medium (2)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Subsets II</a></td> 
   <td>27.0%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Next Permutation</a></td> 
   <td>25.4%</td> 
   <td>Medium (5)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">3Sum Closest</a></td> 
   <td>27.0%</td> 
   <td>Medium (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Palindrome Partitioning</a></td> 
   <td>25.9%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Subsets</a></td> 
   <td>27.9%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Partition List</a></td> 
   <td>27.0%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Construct Binary Tree from Inorder and Postorder Traversal</a></td> 
   <td>26.6%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Construct Binary Tree from Preorder and Inorder Traversal</a></td> 
   <td>26.5%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Combinations</a></td> 
   <td>30.0%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Combination Sum II</a></td> 
   <td>24.7%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Path Sum II</a></td> 
   <td>26.9%</td> 
   <td>Medium (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Permutation Sequence</a></td> 
   <td>22.3%</td> 
   <td>Medium (5)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Permutations</a></td> 
   <td>31.2%</td> 
   <td>Medium (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Sqrt(x)</a></td> 
   <td>22.3%</td> 
   <td>Medium (4)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Combination Sum</a></td> 
   <td>26.8%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Populating Next Right Pointers in Each Node</a></td> 
   <td>35.3%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Spiral Matrix II</a></td> 
   <td>30.8%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Pow(x, n)</a></td> 
   <td>25.9%</td> 
   <td>Medium (3)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Spiral Matrix</a></td> 
   <td>20.6%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Sort List</a></td> 
   <td>20.6%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Clone Graph</a></td> 
   <td>23.0%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Duplicates from Sorted Array II</a></td> 
   <td>30.6%</td> 
   <td>Medium (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Sort Colors</a></td> 
   <td>32.1%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Remove Duplicates from Sorted List II</a></td> 
   <td>24.8%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Zigzag Level Order Traversal</a></td> 
   <td>26.5%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Preorder Traversal</a></td> 
   <td>35.5%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Reorder List</a></td> 
   <td>20.4%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Restore IP Addresses</a></td> 
   <td>20.5%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Single Number II</a></td> 
   <td>33.8%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Reverse Linked List II</a></td> 
   <td>26.1%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Single Number</a></td> 
   <td>45.6%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Reverse Words in a String</a></td> 
   <td>14.0%</td> 
   <td>Medium</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Simplify Path</a></td> 
   <td>19.9%</td> 
   <td>Medium (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Rotate Image</a></td> 
   <td>31.2%</td> 
   <td>Medium (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Rotate List</a></td> 
   <td>22.0%</td> 
   <td>Medium (3)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Inorder Traversal</a></td> 
   <td>35.5%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Set Matrix Zeroes</a></td> 
   <td>30.8%</td> 
   <td>Medium (3)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Search a 2D Matrix</a></td> 
   <td>31.2%</td> 
   <td>Medium (3)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Search for a Range</a></td> 
   <td>27.4%</td> 
   <td>Medium (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Search Insert Position</a></td> 
   <td>34.9%</td> 
   <td>Medium (2)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Search in Rotated Sorted Array II</a></td> 
   <td>30.9%</td> 
   <td>Medium (5)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Text Justification</a></td> 
   <td>14.0%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Search in Rotated Sorted Array</a></td> 
   <td>28.6%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Maximum Path Sum</a></td> 
   <td>20.2%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Reverse Nodes in k-Group</a></td> 
   <td>24.9%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Binary Tree Postorder Traversal</a></td> 
   <td>31.0%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Candy</a></td> 
   <td>19.3%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Edit Distance</a></td> 
   <td>25.5%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Recover Binary Search Tree</a></td> 
   <td>23.7%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Populating Next Right Pointers in Each Node II</a></td> 
   <td>30.7%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Permutations II</a></td> 
   <td>25.0%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Best Time to Buy and Sell Stock III</a></td> 
   <td>22.4%</td> 
   <td>Hard (4)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Palindrome Partitioning II</a></td> 
   <td>18.3%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">N-Queens II</a></td> 
   <td>33.9%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Substring with Concatenation of All Words</a></td> 
   <td>18.1%</td> 
   <td>Hard (3)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Sudoku Solver</a></td> 
   <td>20.9%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">N-Queens</a></td> 
   <td>25.9%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Minimum Window Substring</a></td> 
   <td>18.1%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Merge k Sorted Lists</a></td> 
   <td>21.2%</td> 
   <td>Hard (3)</td> 
   <td>4</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Merge Intervals</a></td> 
   <td>20.9%</td> 
   <td>Hard (4)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Scramble String</a></td> 
   <td>22.8%</td> 
   <td>Hard (5)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Trapping Rain Water</a></td> 
   <td>28.9%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Median of Two Sorted Arrays</a></td> 
   <td>17.6%</td> 
   <td>Hard (5)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Maximal Rectangle</a></td> 
   <td>21.5%</td> 
   <td>Hard (5)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Max Points on a Line</a></td> 
   <td>11.2%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">LRU Cache</a></td> 
   <td>14.1%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Longest Valid Parentheses</a></td> 
   <td>19.7%</td> 
   <td>Hard (4)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Longest Consecutive Sequence</a></td> 
   <td>28.2%</td> 
   <td>Hard (4)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Copy List with Random Pointer</a></td> 
   <td>23.5%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Largest Rectangle in Histogram</a></td> 
   <td>21.5%</td> 
   <td>Hard (5)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Jump Game II</a></td> 
   <td>24.7%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Interleaving String</a></td> 
   <td>19.5%</td> 
   <td>Hard (5)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Insert Interval</a></td> 
   <td>20.7%</td> 
   <td>Hard (4)</td> 
   <td>5</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Wildcard Matching</a></td> 
   <td>14.3%</td> 
   <td>Hard (5)</td> 
   <td>3</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Distinct Subsequences</a></td> 
   <td>25.0%</td> 
   <td>Hard (4)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Word Break II</a></td> 
   <td>16.6%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">First Missing Positive</a></td> 
   <td>22.6%</td> 
   <td>Hard (5)</td> 
   <td>2</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Word Ladder II</a></td> 
   <td>11.5%</td> 
   <td>Hard (1)</td> 
   <td>1</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Find Minimum in Rotated Sorted Array II</a></td> 
   <td>27.9%</td> 
   <td>Hard</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a rel="nofollow">Regular Expression Matching</a></td> 
   <td>20.2%</td> 
   <td>Hard (5)</td> 
   <td>3</td> 
  </tr> 
 </tbody> 
</table>

【2015-6-17】从上次贴出来我的解答以后，最新更新的题目，除了一些需要买书只能在电子书上面看解答的没法验证以外，凡是题目能够在线解答和验证答案的，我把我的全部和分析放在了下面。欢迎指正。

<table style="border-spacing:0px; border-collapse:collapse; margin-bottom:20px; color:#333333; font-family:'Helvetica Neue',Helvetica,Arial,sans-serif; font-size:14px; line-height:20px; widows:1"> 
 <thead style=""> 
  <tr style=""> 
   <th style="padding:8px; line-height:1.42857143; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a href="https://leetcode.com/problemset/algorithms/#" style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">#</a> 
    </div> </th> 
   <th style="padding:8px; line-height:1.42857143; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a href="https://leetcode.com/problemset/algorithms/#" style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Title</a> 
    </div> </th> 
   <th style="padding:8px; line-height:1.42857143; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a href="https://leetcode.com/problemset/algorithms/#" style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Acceptance</a> 
    </div> </th> 
   <th style="padding:8px; line-height:1.42857143; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a href="https://leetcode.com/problemset/algorithms/#" style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Difficulty</a> 
    </div> </th> 
  </tr> 
 </thead> 
 <tbody style=""> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 226</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Invert Binary Tree</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 37.6%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 225</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Implement Stack using Queues</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 30.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 224</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Basic Calculator</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 16.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 223</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Rectangle Area</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 26.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 222</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Count Complete Tree Nodes</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 19.8%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 221</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Maximal Square</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 20.6%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 220</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Contains Duplicate III</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 15.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 219</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Contains Duplicate II</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 26.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 218</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">The Skyline Problem</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 17.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 217</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Contains Duplicate</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 35.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 216</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Combination Sum III</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 27.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 215</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Kth Largest Element in an Array</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 27.4%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 214</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Shortest Palindrome</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 16.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 213</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">House Robber II</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 26.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 212</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Word Search II</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 15.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 211</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Add and Search Word – Data structure design</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 20.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 210</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Course Schedule II</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 19.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 209</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Minimum Size Subarray Sum</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 23.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 208</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Implement Trie (Prefix Tree)</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 25.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 207</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Course Schedule</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 21.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 206</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Reverse Linked List</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 32.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 205</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Isomorphic Strings</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 24.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 204</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Count Primes</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 18.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 203</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Remove Linked List Elements</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 26.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 202</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Happy Number</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 31.5%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 201</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Bitwise AND of Numbers Range</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 27.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 200</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Number of Islands</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 21.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 199</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Binary Tree Right Side View</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 26.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 198</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">House Robber</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 28.8%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 191</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Number of 1 Bits</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 37.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 190</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Reverse Bits</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 28.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 189</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Rotate Array</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 17.8%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 188</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Best Time to Buy and Sell Stock IV</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 17.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 187</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Repeated DNA Sequences</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 19.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 186</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Reverse Words in a String II</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 31.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 179</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Largest Number</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 15.7%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 174</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Dungeon Game</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 17.5%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 173</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Binary Search Tree Iterator</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 29.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 172</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Factorial Trailing Zeroes</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 28.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 171</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Excel Sheet Column Number</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 36.6%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 170</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Two Sum III – Data structure design</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.7%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 169</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Majority Element</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 34.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 168</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Excel Sheet Column Title</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 18.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 167</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Two Sum II – Input array is sorted</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 43.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 166</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Fraction to Recurring Decimal</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 12.6%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 165</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Compare Version Numbers</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 15.1%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 164</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Maximum Gap</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 163</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Missing Ranges</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 24.0%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 162</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Find Peak Element</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 31.4%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 161</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">One Edit Distance</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 24.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 160</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Intersection of Two Linked Lists</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 28.5%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 159</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Longest Substring with At Most Two Distinct Characters</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 30.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 158</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Read N Characters Given Read4 II – Call multiple times</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 22.2%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 157</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Read N Characters Given Read4</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 29.9%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 156</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Binary Tree Upside Down</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 34.4%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 155</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Min Stack</a></td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 18.3%</td> 
   <td style="padding:8px; line-height:1.42857143; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
 </tbody> 
</table>

【Updated：12/15/2015】227到310题

<table style="border-spacing:0px; border-collapse:collapse; width:780px; max-width:100%; margin-bottom:20px; color:#333333; font-family:'Helvetica Neue',Helvetica,Arial,sans-serif; font-size:14px; line-height:20px; widows:1"> 
 <thead style=""> 
  <tr style=""> 
   <th style="padding:8px; width:40px; line-height:1.42857; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">#</a> 
    </div> </th> 
   <th style="padding:8px; width:468px; line-height:1.42857; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Title</a> 
    </div> </th> 
   <th style="padding:8px; width:117px; min-width:100px; line-height:1.42857; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Acceptance</a> 
    </div> </th> 
   <th style="padding:8px; line-height:1.42857; vertical-align:bottom; border-top-width:0px; border-bottom-width:2px; border-bottom-style:solid; border-bottom-color:#dddddd"> 
    <div style=""> 
     <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Difficulty</a> 
    </div> </th> 
  </tr> 
 </thead> 
 <tbody style=""> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 310</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Minimum Height Trees</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 309</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Best Time to Buy and Sell Stock with Cooldown</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 33.7%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 307</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Range Sum Query – Mutable</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 15.5%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 306</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Additive Number</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 23.2%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 304</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Range Sum Query 2D – Immutable</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 20.3%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 303</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Range Sum Query – Immutable</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 23.9%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 301</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Remove Invalid Parentheses</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 28.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 300</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Longest Increasing Subsequence</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 31.8%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 299</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Bulls and Cows</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 25.9%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 297</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Serialize and Deserialize Binary Tree</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 24.2%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 295</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Find Median from Data Stream</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 19.7%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 292</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Nim Game</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 50.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 290</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Word Pattern</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 27.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 289</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Game of Life</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 32.2%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 287</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Find the Duplicate Number</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 36.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 284</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Peeking Iterator</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 31.8%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 283</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Move Zeroes</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 42.3%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 282</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Expression Add Operators</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 21.5%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 279</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Perfect Squares</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 29.8%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 278</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">First Bad Version</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 21.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 275</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">H-Index II</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 31.7%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 274</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">H-Index</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 27.1%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 273</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Integer to English Words</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 16.9%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 268</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Missing Number</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 37.5%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 264</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Ugly Number II</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.5%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 263</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Ugly Number</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 34.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 260</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Single Number III</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 40.7%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 258</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Add Digits</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 47.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 257</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Binary Tree Paths</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.9%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 242</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Valid Anagram</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 39.1%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 241</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Different Ways to Add Parentheses</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 30.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 240</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Search a 2D Matrix II</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 31.4%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 239</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Sliding Window Maximum</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.8%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Hard</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 238</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Product of Array Except Self</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 39.5%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 237</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Delete Node in a Linked List</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 44.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 236</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Lowest Common Ancestor of a Binary Tree</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 27.7%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 235</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Lowest Common Ancestor of a Binary Search Tree</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 37.9%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 234</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Palindrome Linked List</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 25.3%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 233</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Number of Digit One</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 22.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 232</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Implement Queue using Stacks</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 33.8%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 231</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Power of Two</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 33.3%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 230</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Kth Smallest Element in a BST</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 34.0%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 229</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Majority Element II</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 24.2%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 228</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Summary Ranges</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> 21.6%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd"> Easy</td> 
  </tr> 
  <tr style=""> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 227</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> <a style="color:#0088cc; text-decoration:none; background:0px 0px" rel="nofollow">Basic Calculator II</a></td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> 22.2%</td> 
   <td style="padding:8px; line-height:1.42857; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:#dddddd; background-color:#f9f9f9"> Medium</td> 
  </tr> 
 </tbody> 
</table>

**转载请保持完整性并注明来源链接[《四火的唠叨》][Link 1]**

[Link 1]: http://www.raychase.net/2763
[Link 2]: https://docs.google.com/spreadsheet/pub?key=0Aqt--%20wSNYfuxdGxQWVFsOGdVVWxQRlNUVXZTdEpOeEE&output=html
[Link 3]: http://www.raychase.net/2810