包含min的栈

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。

维护一个最小栈,如果当前入栈的数小于等于最小栈的值，则当前节点入栈，否则,不入栈

import java.util.Stack;public class Solution {    private Stack stack = new Stack() ;     private Stack minStack = new Stack() ;         public void push(int node) {        stack.add(node) ;         if(minStack.empty() || node <= minStack.peek()){            minStack.add(node) ;         }     }        public void pop() {        int node = stack.pop() ;         if(node == minStack.peek()){            minStack.pop() ;         }    }        public int top() {        return stack.peek() ;     }        public int min() {        return minStack.peek() ;     }}