Java [leetcode 24]Swap Nodes in Pairs

题目描述：

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.

解题思路：

我只想说递归大法好。

代码如下：

/**

 * 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;

	}

}

巴特西

Java [leetcode 24]Swap Nodes in Pairs

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