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) {
        stack1.push(node);
    }
    
    public int pop() {
        int a = 0;
        stack2.clear();
        while(!stack1.isEmpty()){
            stack2.push(stack1.pop());
        }
        //stack1.clear();

        a = stack2.pop();
        while(!stack2.empty()){
            stack1.push(stack2.pop());
        }
        return a;
    }
}