1 class Queue {
2 stack<int> input,output;
3 public:
4 // Push element x to the back of queue.
5 void push(int x) {
6 input.push(x);
7
8 }
9
10 // Removes the element from in front of queue.
11 void pop(void) {
12 peek();
13 output.pop();
14 }
15
16 // Get the front element.
17 int peek(void) {
18 if(output.empty())
19 {
20 while(!input.empty())
21 {
22 output.push(input.top());
23 input.pop();
24 }
25 }
26 return output.top();
27
28 }
29
30 // Return whether the queue is empty.
31 bool empty(void) {
32 if(input.empty()&&output.empty())
33 return true;
34
35 }
36 };
