LeetCode 反转链表

定义一个函数，输入一个链表的头节点，反转该链表并输出反转后链表的头节点。

示例:

输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL

//第一次
var reverseList = function(head) {
    if(!head) return null
    let per = head
    let next = per.next
    per.next = null

    while(next){
        per = next
        next = per.next
        per.next = head
        head = per
    }
    return per
};

 

//题解后
var reverseList = function(head) {
  let cur = head
  let prev = null
  while(cur){
    cur = cur.next
    head.next = prev
    prev = head
    head = cur
  }
  return prev
};