function ListNode(val) {
  this.val = val;
  this.next = null;
}

var reverseBetween = function (head, m, n) {
  var start = new ListNode();
  start.next = head;
  var result = start;
  var count = 1;
  while (count < m) {
    count  ;
    start = start.next;
  }
  var flag = start;
  start = start.next;
  var flag2 = start;
  var cursor = new ListNode();
  while (count <= n) {
    var temp = new ListNode(start.val);
    var temp1 = temp;
    if (cursor.val != undefined) {
      temp.next = cursor;
    } else {
      flag2 = temp;
    }
    cursor = temp1;
    start = start.next;
    count  ;
  }

  flag2.next = start;
  flag.next = cursor;
  return result.next;
};

var head = new ListNode(1);
var aaa = head;
head.next = new ListNode(-2);
head = head.next;
head.next = new ListNode(-5);
head = head.next;
head.next = new ListNode(0);
head = head.next;
head.next = new ListNode(-4);

console.log(reverseBetween(aaa, 2, 5));