从尾到头打印链表——JavaScript实现

题目：

输入一个链表，按链表值从尾到头的顺序返回一个ArrayList。

思路一：利用栈先入后出的特性完成

思路二：存下来然后进行数组翻转

思路三：利用递归

思路一实现代码：

/*function ListNode(x){
    this.val = x;
    this.next = null;
}*/
function printListFromTailToHead(head)
{
    // write code here
    var res = [];//new an array to save result as a stack
    while(head){//find the last node
        res.unshift(head.val);//save nodes as reverse order
        head = head.next;
    }
    return res;
}

思路二实现代码：

/*function ListNode(x){
    this.val = x;
    this.next = null;
}*/
function printListFromTailToHead(head)
{
    // write code here
    var res = [];//new an array to save result as a stack
    while(head){//find the last node
        res.push(head.val);//save nodes as reverse order
        head = head.next;
    }
    var temp = res.slice(0);//copy the array
    temp.reverse();
    return temp;
}

思路三实现代码：

/*function ListNode(x){
    this.val = x;
    this.next = null;
}*/
var res = [];//new an array to save result as a stack
function printListFromTailToHead(head)
{
    // write code here
    if(res.length!=0) res.length=0;
    if(head!=null){
        if(head.next!=null){//find the last node
        printListFromTailToHead(head.next);
        }
        res.push(head.val);
    }
    
    return res;
}