3.从头到尾打印链表

题目：输入一个链表，从尾到头打印链表每个节点的值。思路：遍历链表，插到数组中

 1 function printListFromTailToHead(head)
 2 {
 3     // write code here
 4     var current = head;
 5     var res = [];
 6     while(current!==null){
 7         res.unshift(current.val)
 8         current = current.next;
 9     }
10     return res;
11 }