包含min函数的栈

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

    public void push(int node) {
        if(stack2.isEmpty()){
            stack1.push(node);
            stack2.push(node);
        }else {
            stack1.push(node);
            if(node<=stack2.peek()){
                stack2.push(node);
            }
        }
    }

    public void pop() {
        int n=stack1.pop();
        if(n==stack2.peek()){
            stack2.pop();
        }
    }

    public int top() {
        return stack1.peek();
    }

    public int min() {
        return stack2.peek();
    }
}