algorithm/Week_01/id_27/LeetCode_24_027.java at master · feixiangcode/algorithm · GitHub

36 lines (30 loc) · 843 Bytes

/**

* Definition for singly-linked list.

* public class ListNode {

* int val;

* ListNode next;

* ListNode(int x) { val = x; }

* }

class Solution {

public ListNode swapPairs(ListNode head) {

ListNode dummyHead = new ListNode(0);

dummyHead.next = head;

if(null == head || null == head.next) return head;

ListNode tail = dummyHead;

ListNode cur = head;

ListNode next = head.next;

while(null !=cur && null != next) {

ListNode tmp = next.next;

cur.next = tmp;

next.next = cur;

if(null != tail) tail.next = next;//与上次操作做连接

tail = cur;//记录这次操作的尾节点

//开启新的一轮操作

cur = tmp;

if(null == cur) break;

next = cur.next;

}

return dummyHead.next;

}

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