剑指Offer之包含min函数的栈

 1 import java.util.Stack;
 2 
 3 public class Solution {
 4     Stack<Integer> stack=new Stack<>();
 5     Stack<Integer> smin=new Stack<>();
 6     
 7     public void push(int node) {
 8         stack.push(node);
 9         if(smin.isEmpty())
10             smin.push(node);
11         if(node<=smin.peek())
12             smin.push(node);
13     }
14     
15         public void pop() {
16             if(smin.peek()==stack.peek())
17                 smin.pop();
18             stack.pop();
19         }
20         
21         public int top() {
22             return stack.peek();
23         }
24         
25         public int min() {
26             return smin.peek();
27         }
28 }