priority_queue

实际上是以 堆 的规则组织起来的数组，是一颗完全二叉树

**反函数 !!!

堆的向上向下调整

#pragma once

namespace xiong
{
	//反函数
	template<class T>
	struct less
	{
		bool operator()(const T& x, const T& y)
		{
			return x < y;
		}
	};
	template<class T>
	struct greater
	{
		bool operator()(const T& x, const T& y)
		{
			return x > y;
		}
	};

	template<class T, class Container = vector<T>, class Compare = less<T>>
	class priority_queue
	{
	public:
		void adjust_up(size_t child)
		{
			size_t parent = (child - 1) / 2;
			while (child > 0)
			{
				if (Compare()(_con[parent], _con[child]))
				{
					swap(_con[child], _con[parent]);
					child = parent;
					parent = (child - 1) / 2;
				}
				else break;
			}
		}
		void adjust_down(size_t parent)
		{
			size_t child = 2 * parent + 1;
			while (child < _con.size())
			{
				if (child + 1 < _con.size() && Compare()(_con[child], _con[child + 1]))
				{
					child++;
				}
				if (Compare()(_con[parent], _con[child]))
				{
					swap(_con[child], _con[parent]);
					parent = child;
					child = 2 * parent + 1;
				}
				else
				{
					break;
				}
			}
		}

		void push(const T& val)
		{
			_con.push_back(val);
			adjust_up(_con.size() - 1);
		}
		void pop()
		{
			assert(!_con.empty());
			swap(_con[0], _con[_con.size() - 1]);
			_con.pop_back();
			adjust_down(0);
		}
		const T& top() 
		{
			return _con.front();
		}
		bool empty() 
		{
			return _con.empty();
		}
		size_t size()
		{
			return _con.size();
		}
	private:
		Container _con;
	};
}