题解 | 用两个栈实现队列

import java.util.*;
import java.util.Stack;

public class Solution {
    Stack<Integer> stack1 = new Stack<Integer>();
    Stack<Integer> stack2 = new Stack<Integer>();

    public void push(int node) {
        while (!stack1.isEmpty()) {
            Integer pop = stack1.pop();
            stack2.push(pop);
        }
        stack1.push(node);

        while (!stack2.isEmpty()) {
            Integer pop = stack2.pop();
            stack1.push(pop);
        }
    }

    public int pop() {
        return stack1.pop();
    }
}