LeetCode: 232. Implement Queue using Stacks

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LeetCode: 232. Implement Queue using Stacks
タイトルの説明
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. Example:
MyQueue queue = new MyQueue();

queue.push(1);
queue.push(2);  
queue.peek();  // returns 1
queue.pop();   // returns 1
queue.empty(); // returns false

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).

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    ACコード
    class MyQueue {
    public:
        /** Initialize your data structure here. */
        MyQueue() {
            
        }
        
        /** Push element x to the back of queue. */
        void push(int x) {
            m_stk.push(x);
        }
        
        /** Removes the element from in front of queue and returns that element. */
        int pop() {
            if(m_que.empty())
            {
                MoveStk2Que();
            }
            
            int front = m_que.top();
            m_que.pop();
            return front;
        }
        
        /** Get the front element. */
        int peek() {
            if(m_que.empty())
            {
                MoveStk2Que();
            }
            
            return m_que.top();
        }
        
        /** Returns whether the queue is empty. */
        bool empty() {
            return (m_stk.empty() && m_que.empty());
        }
    private:
        void MoveStk2Que()
        {
            while(!m_stk.empty())
            {
                m_que.push(m_stk.top());
                m_stk.pop();
            }
        }
    private:
        stack m_stk;
        stack m_que;
    };
    
    /**
     * Your MyQueue object will be instantiated and called as such:
     * MyQueue obj = new MyQueue();
     * obj.push(x);
     * int param_2 = obj.pop();
     * int param_3 = obj.peek();
     * bool param_4 = obj.empty();
     */