LeetCode: Min Stack 解题报告

 1 class MinStack {
 2     Stack<Integer> elements = new Stack<Integer>();
 3     Stack<Integer> minStack = new Stack<Integer>();
 4     
 5     public void push(int x) {
 6         elements.push(x);
 7         if (minStack.isEmpty() || x <= minStack.peek()) {
 8             minStack.push(x);
 9         }
10     }
11 
12     public void pop() {
13         if (elements.isEmpty()) {
14             return;
15         }
16         
17         // 这个地方太蛋疼了，居然要用equals...
18         if (elements.peek().equals(minStack.peek())) {
19             minStack.pop();
20         }
21         elements.pop();
22     }
23 
24     public int top() {
25         return elements.peek();       
26     }
27 
28     public int getMin() {
29         return minStack.peek();
30     }
31 }