剑指 Offer 06. 从尾到头打印链表

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
 
 /*
    1.用一个栈，来实现倒序输出（本题）
    2.改变结构，将链表先翻转，后输出
 */
class Solution {
    public int[] reversePrint(ListNode head) {
        LinkedList<Integer> stack = new LinkedList<>();
        //将链表元素压入栈
        while(head!= null){
            stack.addLast(head.val);
            head = head.next;
        }
        int[] res = new int[stack.size()];
        //将栈中的元素 出栈，赋值给数组res
        for(int i = 0;i < res.length;i++){
            res[i] = stack.removeLast();
        }
        return res;
    }
}

class Solution {
    public int[] reversePrint(ListNode head) {
        Stack<Integer> stack = new Stack<>();
        //将链表元素压入栈
        while(head!= null){
            stack.push(head.val);
            head = head.next;
        }
        int[] res = new int[stack.size()];
        //将栈中的元素 出栈，赋值给数组res
        for(int i = 0;i < res.length;i++){
            res[i] = stack.pop();
        }
        return res;
    }
}