10 Implement queue using stack

[zwkcoding]

Solution:

class Queue {
    stack <int> input, output;
    public:
        void push(int x)  {
            input.push(x);
        }

        void pop(void)  {
            peek();
            output.pop()
        }

        int peek(void)  {
            if (output.empty())
                while(input.size())
                    output.push(input.top());
                    input.pop();
            return output.top();
        }

        bool empty(void)  {
            return input.empty() && output.empty();
        }
};

NOTE: Above Solution's Time Complexity is O(1), using amortized cost.