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leetcode 1721. 交换链表中的节点

作者:互联网

给你链表的头节点 head 和一个整数 k 。

交换 链表正数第 k 个节点和倒数第 k 个节点的值后,返回链表的头节点(链表 从 1 开始索引)。

 

示例 1:


输入:head = [1,2,3,4,5], k = 2
输出:[1,4,3,2,5]
示例 2:

输入:head = [7,9,6,6,7,8,3,0,9,5], k = 5
输出:[7,9,6,6,8,7,3,0,9,5]
示例 3:

输入:head = [1], k = 1
输出:[1]
示例 4:

输入:head = [1,2], k = 1
输出:[2,1]
示例 5:

输入:head = [1,2,3], k = 2
输出:[1,2,3]
 

提示:

链表中节点的数目是 n
1 <= k <= n <= 105
0 <= Node.val <= 100

来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/swapping-nodes-in-a-linked-list
著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode swapNodes(ListNode head, int k) {
        ListNode f = new ListNode(0);
        f.next = head;
        ListNode a = f;
        int n = 1;
        while (n < k) {
            a = a.next;
            n++;
        }
        ListNode b = f;
        ListNode c = a.next.next;
        while (c != null) {
            b = b.next;
            c = c.next;
        }
        c = a.next;
        a.next = b.next;
        b.next = c;
        a = a.next;
        b = b.next;
        c = a.next;
        a.next = b.next;
        b.next = c;
        return f.next;
    }
}

标签:head,ListNode,val,示例,next,链表,1721,leetcode
来源: https://www.cnblogs.com/wangzaiguli/p/14767569.html