题解 | 用两个栈实现队列

stack1保存元素，stack2用来拿到最先push的元素

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() {
        while(!stack1.isEmpty()){
            stack2.push(stack1.pop());
        }
        int res=stack2.pop();
        while(!stack2.isEmpty()){
            stack1.push(stack2.pop());
        }
        return res;
    
    }
}