前置知识：仿函数

template<class T>
struct  Less
{
	bool operator()(const T& x, const T& y) // 
	{
		return x < y;
	}
};

priority_queue的模拟实现

通过对priority_queue的底层结构就是堆，因此此处只需对对进行通用的封装即可

template<class T>
struct  Less
{
	bool operator()(const T& x, const T& y) // 
	{
		return x < y;
	}
};
// 构造器 
template<class T, class Container = vector<T>,class compare = Less<T>>

class priority 
{
	Container container;
	compare com;
public:
	void adjust_up(size_t child)
	{
		while (child > 0) 
		{
			size_t parent = (child - 1) / 2;
			//if (container[parent] < container[child]) 
			if(com(container[parent],container[child]))
			{
				std::swap(container[parent], container[child]);
				child = parent;
				parent = (child - 1) / 2;
			}
			else 
			{
				break;
			}

		}
	}
	void push(const T& x) 
	{
		container.push_back(x);
		adjust_up(container.size() - 1);
	}
	T top() 
	{
		return container[0];
	}
	void adjust_down(size_t parent) 
	{
		size_t child = parent * 2 + 1;
		int n = container.size();
		while (child < n) 
		{
			//if (child + 1 < n && container[child + 1] > container[child]) child++;
		//	if (child + 1 < n && container[child]  <   container[child + 1]) child++;
			if (child + 1 < n && com(container[child], container[child + 1])) child++;
			//if (container[parent] < container[child]) 
			if(com(container[parent], container[child]))
			{
				std::swap(container[parent], container[child]);
				parent = child;
				child = parent * 2 + 1;
			}
			else 
			{
				break;
			}
		}
	}
	void pop() 
	{
		std::swap(container[0], container[container.size() - 1]);
		container.pop_back();
		adjust_down(0);

	}
	bool empty() 
	{
		return container.empty();
	}
};