[剑指offer]用两个栈实现队列

题目描述

用两个栈来实现一个队列，完成队列的Push和Pop操作。 队列中的元素为int类型。

 

题目链接：

https://www.nowcoder.com/practice/54275ddae22f475981afa2244dd448c6?tpId=13&tqId=11158&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

 

 

 

package com.sunshine.OFFER66_SECOND;

import org.junit.Test;

import java.util.Stack;

public class A5_pushpop {

    @Test
    public void test(){
        push(1);
        push(2);
        push(3);
        push(4);
        System.out.println(pop());
        System.out.println(pop());
        System.out.println(pop());
        System.out.println(pop());
    }


    Stack<Integer> stack1 = new Stack<Integer>();
    Stack<Integer> stack2 = new Stack<Integer>();

    public void push(int node) {
        stack1.push(node);
    }

    public int pop() {
        if(!stack2.empty()){
            return stack2.pop();
        }
        while(!stack1.empty()){
            stack2.push(stack1.pop());
        }
        return stack2.pop();
    }
}