从尾到头打印链表

输入一个链表的头节点，从尾到头反过来返回每个节点的值（用数组返回）。

输入：head = [1,3,2]
输出：[2,3,1]

两种解法：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public int[] reversePrint(ListNode head) {
        /**
         *解法二：Stack
         */
        Stack<Integer> stack = new Stack<Integer>();
        int size = 0;   //数组长度
        while(head != null){
            stack.push(head.val);
            head = head.next;
            size++;
        }
        int[] ans = new int[size];
        for(int i = 0; i < size; i++){
            ans[i] = stack.pop();
        }
        return ans;
        /**
         *解法一
         */
        /**
        ListNode temp = head;
        int length = 0;
        while(head != null){
            length++;
            head = head.next;
        }
        int[] ans = new int[length];
        for (int i = length-1; i >= 0; i--){
            ans[i] = temp.val;
            temp = temp.next;
        }
        return ans;
        **/
    }
}