剑指offer-包含min函数的栈

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);
        if(stack2.empty())
            stack2.push(node);
        if(node<stack2.peek())
            stack2.push(node);
        
    }
    
    public void pop() {
        if(stack1.peek()==stack2.peek()){
            stack1.pop();
            stack2.pop();
        }
        else{
            stack1.pop();
        }
        
    }
    
    public int top() {
        return stack1.peek();
        
    }
    
    public int min() {
        return stack2.peek();
        
    }
}