[LeetCode][JavaScript]Reverse Linked List II

 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} m
11  * @param {number} n
12  * @return {ListNode}
13  */
14 var reverseBetween = function(head, m, n) {
15     var res = new ListNode(-1), subHead = res, count = 1;
16     res.next = head;
17     while(count !== m){
18         subHead = head;
19         head = head.next;
20         count++;
21     }
22     var subTail = head, tmp;
23     while(count !== n + 1){
24         tmp = head.next;
25         head.next = subHead.next;
26         subHead.next = head;
27         head = tmp;
28         count++;
29     }
30     subTail.next = head;
31     return res.next;
32 };