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[LeetCode] Swap Nodes in Pairs

时间:2014-08-30 01:11:08      阅读:286      评论:0      收藏:0      [点我收藏+]

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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.

 

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode swapPairs(ListNode head) {
        if (head == null || head.next == null) return head;
        
        ListNode nowNode = new ListNode(0);
        nowNode.next = head;
        head = head.next;
        
        while (nowNode.next != null && nowNode.next.next != null) {
            ListNode tmp = nowNode.next;
            nowNode.next = tmp.next;
            tmp.next = nowNode.next.next;
            nowNode.next.next = tmp;
            nowNode = tmp;
        }
        
        return head;
    }
}

 

[LeetCode] Swap Nodes in Pairs

标签:des   style   blog   color   io   strong   for   div   log   

原文地址:http://www.cnblogs.com/yuhaos/p/3945978.html

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