算法导论2nd 10.1-7

思路：两个队列q1和q2，两个队列指针pusher和poper分别指向q1和q2，push时调用pusher->enqueue，然后将poper里的元素全部dequeue并enqueue到pusher，最后交换pusher和poper。

#include <iostream>

class Queue
{
    int *array;
    int head, tail, size;

    Queue(Queue &&q) = delete;
    Queue(const Queue &q) = delete;
    Queue &operator=(const Queue &q) = delete;

public:
    Queue(int n)
    {
        size = n + 1;
        array = new int [size];
        head = 0;
        tail = 0;
    }

    ~Queue()
    {
        if (array)
        {
            delete [] array;
            array = NULL;
            size = -1;
            head = -1;
            tail = -1;
        }
    }

    bool enqueue(int x)
    {
        if (full())
            return false;
        array[tail++] = x;
        if (tail >= size)
            tail = 0;
        return true;
    }

    bool dequeue(int &res)
    {
        if (empty())
            return false;
        res = array[head++];
        if (head >= size)
            head = 0;
        return true;
    }

    bool empty()
    {
        return head == tail;
    }

    bool full()
    {
        return (tail + 1) % size == head;
    }
};

class Stack
{
    Queue q1, q2, *pusher, *poper;
    int size;

public:
    Stack(int n) : q1(n), q2(n)
    {
        pusher = &q1;
        poper = &q2;
    }

    bool push(int x)
    {
        if (poper->full())
            return false;
        pusher->enqueue(x);
        while (poper->dequeue(x))
            pusher->enqueue(x);
        Queue *tmp = pusher;
        pusher = poper;
        poper = tmp;
        return true;
    }

    bool pop(int &res)
    {
        return poper->dequeue(res);
    }
};

int main()
{
    int t;
    Queue queue(4);
    queue.enqueue(1);
    queue.dequeue(t);
    queue.enqueue(2);
    queue.dequeue(t);
    queue.enqueue(3);
    queue.enqueue(4);
    queue.enqueue(5);
    queue.enqueue(6);
    queue.enqueue(7);
    while (queue.dequeue(t))
        std::cout << t << std::endl;
    queue.enqueue(8);
    queue.enqueue(9);
    queue.enqueue(10);
    queue.enqueue(11);
    queue.enqueue(12);
    while (queue.dequeue(t))
        std::cout << t << std::endl;
    Stack stack(4);
    stack.push(1);
    stack.push(2);
    stack.push(3);
    stack.push(4);
    stack.push(5);
    while(stack.pop(t))
        std::cout << t << std::endl;
    return 0;
}