队列中取最大值操作问题（编程之美3.7）

#include "stdafx.h"
const int MAXN = 100;

class stack
{
public:
	stack()
	{
		stackTop = -1;
		maxItemIndex = -1;
	}
	void Push(int x)
	{
		stackTop ++;
		if(stackTop >= MAXN)
			;
		else
		{
			items[stackTop]=x;
			if(x>Max())
			{
				nextMaxItem[stackTop] = maxItemIndex;
				maxItemIndex = stackTop;
			}
			else
				nextMaxItem[stackTop] = -1;
		}
	}
	int Pop()
	{
		int x;
		if(stackTop < 0)
			return -1;
		else
		{
			x = items[stackTop];
			if(stackTop == maxItemIndex)
			{
				maxItemIndex = nextMaxItem[stackTop];
			}
			stackTop--;
		}
		return x;
	}
	int Max()
	{
		if(maxItemIndex >= 0)
			return items[maxItemIndex];
		else
			return -1;
	}
	bool empty()
	{
		return stackTop == -1;
	}

private:
	int items[MAXN];
	int stackTop;
	int nextMaxItem[MAXN];
	int maxItemIndex;

};

class Queue
{
public:
	void Enqueue(int x)
	{
		B.Push(x);
	}
	int Dequeue()
	{
		if(A.empty())
		{
			while(B.empty())
			{
				A.Push(B.Pop());
			}
		}
		return A.Pop();
	}
	int Max()
	{
		if(A.Max() >= B.Max())
			return A.Max();
		else
			return B.Max();
	}
private:
	stack A;
	stack B;
};

int _tmain(int argc, _TCHAR* argv[])
{

	Queue q;
	q.Enqueue(10);
	q.Enqueue(100);
	q.Dequeue();
	q.Enqueue(5);
	printf("%d", q.Max());
	return 0;
}