【栈】155. 最小栈

 1 class MinStack {
 2 public:
 3     /** initialize your data structure here. */
 4     MinStack() 
 5     {
 6         
 7     }
 8     
 9     void push(int x) 
10     {
11         s1.push(x);
12         if(s2.empty())
13         {
14             s2.push(x);
15         }
16         else
17         {
18             int t = s2.top();
19             s2.push((x < t) ? x : t);
20         }
21     }
22     
23     void pop() 
24     {
25         s1.pop();
26         s2.pop();
27     }
28     
29     int top() 
30     {
31         return s1.top();
32     }
33     
34     int getMin() 
35     {
36         return s2.top();
37     }
38 private:
39     stack<int> s1;
40     stack<int> s2;
41 };
42 
43 /**
44  * Your MinStack object will be instantiated and called as such:
45  * MinStack* obj = new MinStack();
46  * obj->push(x);
47  * obj->pop();
48  * int param_3 = obj->top();
49  * int param_4 = obj->getMin();
50  */