【剑指offer】从尾到头打印链表

题目描述

  输入一个链表，按链表值从尾到头的顺序返回一个ArrayList。

Java版本1实现

/**
*    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> list = new ArrayList<>();
        ListNode head = listNode;
        while(head != null){
            list.add(0,head.val);
            head = head.next;
        }
        return list;
    }
}

Java版本2实现

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

Python版本1实现

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    # 返回从尾部到头部的列表值序列，例如[1,2,3]
    def printListFromTailToHead(self, listNode):
        # write code here
        list = []
        head = listNode
        while head:
            list.insert(0, head.val)
            head = head.next
        return list    

Python版本2实现

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    # 返回从尾部到头部的列表值序列，例如[1,2,3]
    def printListFromTailToHead(self, listNode):
        # write code here
        list = []
        head = listNode
        while head:
            list.append(head.val)
            head = head.next
        list.reverse()
        return list