题解 | #从尾到头打印链表#

import java.util.*;
/**
*    public class ListNode {
*        int val;
*        ListNode next = null;
*
*        ListNode(int val) {
*            this.val = val;
*        }
*    }
*
*/
import java.util.ArrayList;
public class Solution {
    public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        ArrayList<Integer> res = new ArrayList<Integer>();
        //re(listNode,res);//递归
	  
	   //栈
        Stack<Integer> stack = new Stack<Integer>();
        while(listNode!=null){
            stack.push(listNode.val);
            listNode=listNode.next;
        }
        while(!stack.isEmpty()){
            res.add(stack.pop());
        }	  
        return res;
    }

    public void re(ListNode listNode,ArrayList<Integer> list){
        if(listNode != null){
            re(listNode.next,list);
            list.add(listNode.val);
        }
    }
}

思路1：递归

思路2：栈

时间：O(n)

空间：O(n)