用两个栈实现队列（非转载）

就是酱紫：

#include<iostream>
#include<stack>
using namespace std;
struct my_queue
{
	stack<int> s1, s2;
};

void enqueue(my_queue &q, int value)
{
	q.s1.push(value);
}

int dequeue(my_queue &q)
{
	if(q.s2.empty())
	{
		while(!q.s1.empty())
		{
			q.s2.push(q.s1.top());
			q.s1.pop();
		}
	}
	if(q.s2.empty())
	{
		cerr << "The queue is empty/n";
		exit(1);
	}
	int temp = q.s2.top();
	q.s2.pop();
	return temp;
}

int main()
{
	my_queue q;
	enqueue(q,1);
	enqueue(q,2);
	cout << dequeue(q)<<endl;
}