Java [leetcode 24]Swap Nodes in Pairs

標籤：

題目描述：

Given a linked list, swap every two adjacent nodes and return its head.

For example,
Given 1->2->3->4, you should return the list as 2->1->4->3.

Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.

解題思路：

我只想說遞迴大法好。

代碼如下：

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode swapPairs(ListNode head) {if (head == null)return null;if (head.next == null)return head;ListNode tmp = head.next;ListNode forward = head.next.next;tmp.next = head;head.next = swapPairs(forward);return tmp;}}

 

Java [leetcode 24]Swap Nodes in Pairs