面试题 03.05. 栈排序

 1 class SortedStack {
 2 public:
 3     stack<int>s1;
 4     stack<int>s2;
 5     SortedStack() 
 6     {
 7 
 8     }
 9     
10     void push(int val) 
11     {
12         while(!s1.empty()&&s1.top()<val)
13         {
14             s2.push(s1.top());
15             s1.pop();
16         }
17         s1.push(val);
18         while(!s2.empty())
19         {
20             s1.push(s2.top());
21             s2.pop();
22         }
23     }
24     
25     void pop() 
26     {
27         if(!s1.empty())
28         {
29             s1.pop();
30         }
31     }
32     
33     int peek() 
34     {
35       if(!s1.empty())
36       {
37             return s1.top();
38         }
39         return -1;
40     }
41     
42     bool isEmpty() 
43     {
44         return s1.empty();
45     }
46 };
47 
48 /**
49  * Your SortedStack object will be instantiated and called as such:
50  * SortedStack* obj = new SortedStack();
51  * obj->push(val);
52  * obj->pop();
53  * int param_3 = obj->peek();
54  * bool param_4 = obj->isEmpty();
55  */