500. Keyboard Row（判断单词能否由键盘上的某一行字符表示）

阳光穿透心脏的1/2处 2022-09-28 14:26 10阅读 0赞

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

![American keyboard][]

Example 1:

Input: ["Hello", "Alaska", "Dad", "Peace"]
    Output: ["Alaska", "Dad"]

Note:

1.  You may use one character in the keyboard more than once.
2.  You may assume the input string will only contain letters of alphabet.

题目大意：给定一组字符串，判断其中哪些可以由键盘上的某一行字母表示，输出满足条件的字符串所构成的字符串数组。

解题思路：定义一个长度为26的整型数组keyboard，keyboard\[i\]表示字符‘a’+1属于键盘上的第几行字母（第一行，第二行，或者第三行）。对每一个字符串进行判断，如果每一个字符都在同一行，则该字符串满足条件，否则不满足。

代码如下：（3ms，beats 82.87%）

public String[] findWords(String[] words) {
            int[] keyboard = new int[] { 2, 3, 3, 2, 1, 2, 2, 2, 1, 2, 2, 2, 3, 3, 1, 1, 1, 1, 2, 1, 1, 3, 1, 3, 1, 3 };
    		String[] temp = new String[words.length];
    		int index = 0;
    		for (String word : words) {
    			char[] chars = word.toLowerCase().toCharArray();
    			int len = chars.length;
    			if (len == 0)
    				break;
    			int row = keyboard[chars[0] - 'a'];
    			int i;
    			for (i = 0; i < len; i++) {
    				if (keyboard[chars[i] - 'a'] != row)
    					break;
    			}
    			if (i == len)
    				temp[index++] = word;
    		}
    		String[] res = new String[index];
    		for(int i=0;i<index;i++)
    			res[i] = temp[i];
    		return res;
        }

[American keyboard]: https://leetcode.com/static/images/problemset/keyboard.png