问题描述
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.
code
/*
比较简单
脑子清醒就行
*/
/**
* 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 newHead = new ListNode(0);
newHead.next = head;
ListNode p = newHead;
while(p.next != null && p.next.next != null) {
ListNode temp = p.next;
p.next = temp.next;
temp.next = p.next.next;
p.next.next = temp;
p = temp;
}
return newHead.next;
}
}