题目描述
定义栈的数据结构，请在该类型中实现一个能够得到栈最小元素的min函数。

import java.util.Stack;
public class Solution {
    
    private Stack stack1;
    private Stack stack2;
    Solution () {
        
        stack1 = new Stack();
        stack2 = new Stack();
    }
    public void push(int node) {
        stack1.push(node);
        if(stack2.isEmpty()) {
            
            stack2.push(node);
        }else {
            
            if(node <= (int)stack2.peek()) {
                
                stack2.push(node);
            }else {
                
                stack2.push(stack2.peek());
            }
        }
    }
    public void pop() {
        
        stack1.pop();
        stack2.pop();
    }
    public int top() {
        
        return (int)stack1.peek();
    }
    public int min() {
        
        return (int)stack2.peek();
    }
}