题目

https://www.nowcoder.com/practice/54275ddae22f475981afa2244dd448c6?tpId=190&rp=1&ru=%2Factivity%2Foj&qru=%2Fta%2Fjob-code-high-rd%2Fquestion-ranking

import java.util.Stack;

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

    public void push(int node) {
        Integer data;
        while(stack2.size()!=0)
        {
            stack1.push(stack2.pop());
        }
        stack2.push(node);
        while(stack1.size()!=0)
        {
            stack2.push(stack1.pop());
        }
    }

    public int pop() {
        if(stack2.size()!=0)
        {
            return stack2.pop();
        }
         return 0;
    }
}