[LeetCode] Implement Stack using Queues

 1 class Stack {
 2 private:
 3     queue<int> que[2];
 4     int cur = 0;
 5     
 6 public:
 7     // Push element x onto stack.
 8     void push(int x) {
 9         que[cur].push(x);
10     }
11 
12     // Removes the element on top of the stack.
13     void pop(void) {
14         while (que[cur].size() > 1) {
15             que[1 - cur].push(que[cur].front());
16             que[cur].pop();
17         }
18         que[cur].pop();
19         cur = 1 - cur;
20     }
21 
22     // Get the top element.
23     int top(void) {
24         while (que[cur].size() > 1) {
25             que[1 - cur].push(que[cur].front());
26             que[cur].pop();
27         }
28         int top = que[cur].front();
29         que[1 - cur].push(que[cur].front());
30         que[cur].pop();
31         cur = 1 - cur;
32         return top;
33     }
34 
35     // Return whether the stack is empty.
36     bool empty(void) {
37         return que[cur].empty();
38     }
39 };