LeetCode 24. Swap Nodes in Pairs (两两交换链表中的节点)

待我称王封你为后i 2023-08-17 16:45 51阅读 0赞

题目标签：Linked List

题目给了我们一组 linked list，让我们把每对nodes 互换位置。

新键一个dummy node，然后遍历list，每次建立 s1 和 s2 记录两个点，然后互换位置，具体看code。

Java Solution:

Runtime:  0 ms, faster than 100 %

Memory Usage: 34 MB, less than 100 %

完成日期：05/22/2019

关键点：换位置时候先后顺序

/**
     * Definition for singly-linked list.
     * public class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode(int x) { val = x; }
     * }
     */
    class Solution {
        public ListNode swapPairs(ListNode head) {
            ListNode dummy = new ListNode(0);
            dummy.next = head;
            ListNode p = dummy;
            
            while(p.next != null && p.next.next != null) {
                ListNode s1 = p.next;
                ListNode s2 = p.next.next;
                
                // step 1: p -> s2
                p.next = s2;
                // step 2: s1 -> s2.next
                s1.next = s2.next;
                // step 3: s2 -> s1
                s2.next = s1;
                // step 4: p = s1
                p = s1;
            }
            return dummy.next;
        }
    }

参考资料：LeetCode Discuss[  
][Link 1]

LeetCode 题目列表 - [LeetCode Questions List][]

题目来源：https://leetcode.com/

转载于:https://www.cnblogs.com/jimmycheng/p/11397727.html

[Link 1]: https://leetcode.com/problems/daily-temperatures/discuss/?currentPage=1&orderBy=recent_activity&query=
[LeetCode Questions List]: http://www.cnblogs.com/jimmycheng/p/7119334.html