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

function printListFromTailToHead(head)
{
    // write code here
    var current = head;
    var res = [];
    while(current!==null){
        res.unshift(current.val)
        current = current.next;
    }
    return res;
}