1 /**
2 * Definition for singly-linked list.
3 * function ListNode(val) {
4 * this.val = val;
5 * this.next = null;
6 * }
7 */
8 /**
9 * @param {ListNode} head
10 * @param {number} n
11 * @return {ListNode}
12 */
13
14 function ListNode(val) {
15 this.val = val;
16 this.next = null;
17 }
18
19 var removeNthFromEnd = function(head, n) {
20 if (head === null) {
21 return null;
22 }
23
24 var p1 = p2 = head;
25
26 //p1先移动n次
27 for (var i = 0; i < n; i++) {
28 p1 = p1.next;
29 }
30
31 //要移除的是第一个元素
32 if (p1 === null) {
33 return head.next;
34 }
35
36 //当p1指向最后一个结点，则p2.next即为要删除的结点
37 while (p1.next !== null) {
38 p1 = p1.next;
39 p2 = p2.next;
40 }
41
42 //删除倒数第n个结点
43 p2.next = p2.next.next;
44
45 return head;
46 };
