【leetcode】206.反转链表js

题目

思路

偷个懒贴个链接了，迭代和递归的思路都有：【leetcode】206.反转链表

代码

/**
 * 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 reverseList = function(head) {
    let pre = null
    let cur = head
    while (cur !== null) {
        let tmp = cur.next
        cur.next = pre
        pre = cur
        cur = tmp
    }
    return pre
};

时间复杂度为O(n)