[Leetcode] Min Stack

 1 class MinStack {
 2         Stack<Integer> vals=new Stack<Integer>();
 3         Stack<Integer> mins=new Stack<Integer>();
 4         public void push(int x) {
 5             vals.push(x);
 6             if(!mins.isEmpty()){
 7                 int temp=mins.peek();
 8                 if(temp>=x){　　　　　　//注意此处！！！在temp=x的时候也要push进去！！！想想[2,0,3,0]
 9                     mins.push(x);
10                 }
11             }else{
12                 mins.push(x);
13             }
14         }
15 
16         public void pop() {
17             if(!vals.isEmpty()){
18                 int x=vals.pop();
19                 if(!mins.isEmpty()){
20                     if(x==mins.peek()){
21                         mins.pop();
22                     }
23                 }else{
24                     return;
25                 }
26             }else{
27                 return;
28             }
29         }
30 
31         public int top() {
32             if(!vals.isEmpty()){
33                 return vals.peek();
34             }else{
35                 return 0;
36             }
37         }
38 
39         public int getMin() {
40             if(!mins.isEmpty()){
41                 return mins.peek();
42             }else{
43                 return 0;
44             }
45         }
46     }