p24

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LeetCode p24 Swap Nodes in Pairs 题解

1.题目：

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.

题意：

按如上方式每2个交换链表中的值

2.解题思路:

见代码，直接交换值，注意边界。

3.代码

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/**
 * 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) {
        ListNode ans = head;
		while (head != null && head.next != null) {
			int c = head.val;
			head.val = head.next.val;
			head.next.val = c;
			head = head.next.next;
		}
		return ans;

    }
}

4.一些总结：