LeetCode OJのImplement Queue using Stacks(スタックを使用してキューを実装)

タイトル:
Implement the following operations of a queue using stacks.
push(x) -- Push element x to the back of queue.
pop() -- Removes the element from in front of queue.
peek() -- Get the front element.
empty() -- Return whether the queue is empty.
Notes:
You must use only standard operations of a stack -- which means only  push to top ,  peek/pop from top ,  size , and  is empty  operations are valid.
Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).
考え方:
2つのスタックを使用し、1つのスタックはデータを格納し、もう1つのスタックは移行に使用します.pushが必要な場合、pushは最初のスタックに行きます.popが必要な場合、スタック1のデータをスタック2に移行し、スタックの底はpopのデータである.
コード:

class Queue {
public:
    stack<int> input , output;
    // Push element x to the back of queue.
    void push(int x) 
    {
        input.push(x);
    }

    // Removes the element from in front of queue.
    void pop(void) 
    {
        peek();
        output.pop();
    }

    // Get the front element.
    int peek(void) 
    {
        if(output.empty())
        {
            while(!input.empty())
            {
                output.push(input.top());
                input.pop();
            }
        }
        return output.top();
    }

    // Return whether the queue is empty.
    bool empty(void) 
    {
        return input.empty() && output.empty();
    }
};