题目描述

开始以为能用Stack,后面发现不行。（是默认添加相关类？）

Java 代码不使用栈

/**
 * Definition for singly-linked list.
 * class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public int[] printListReversingly(ListNode head) {
        ListNode p = head;
        int count = 0;
        while (p != null){
            p = p.next;
            count++;
        }
        int[] result = new int[count];
        p = head;
        for (int i = count - 1; i >= 0; i--) {
            result[i] = p.val;
            p = p.next;
        }
        return result;
    }
}

Java 代码使用栈

    public int[] printListReversingly(ListNode head) {
        Stack<Integer> stack = new Stack<>();
        ListNode p = head;
        int count = 0;
        while (p != null){
            stack.push(head.val);
            p = p.next;
            count++;
        }
        int[] result = new int[count];
        for (int i = 0; i < result.length; i++) {
            result[i] = stack.pop();
        }
        return result;
    }