24.两两交换链表中的节点.js

/*
 * @lc app=leetcode.cn id=24 lang=javascript
 *
 * [24] 两两交换链表中的节点
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var swapPairs = function (head) {
	if (head === null || head.next === null) {
		return head;
	}
	let nxt = head.next;
	head.next = swapPairs(nxt.next);
	nxt.next = head;
	return nxt;
};
// @lc code=end