优先队列

优先队列

核心代码

#pragma once
#include<iostream>
#include<vector>
#include<list>

using namespace std;

namespace mudan
{
	//大堆
	//Compare进行比较的仿函数 less -> 大堆    greater -> 小堆     
	template<class T, class Container = vector<T>,class Compare=std::less<T>>
	class priority_queue
	{
	public:
		priority_queue()
		{}

		template<class InputIterator>
		priority_queue(InputIterator first, InputIterator last)
		{
			while (first != last)
			{
				_con.push_back(*first);
				first++;
			}

			for (int i = (_con.size() - 1 - 1) / 2; i >= 0; i--)
			{
				Adjust_down(i);
			}
		}

		size_t size()
		{
			return _con.size();
		}

		void Adjust_up(size_t child)
		{
			Compare compare;
			size_t parent = (child - 1) / 2;
			while (child>0)
			{
				if (compare(_con[parent],_con[child]))
				{
					std::swap(_con[parent], _con[child]);
					child = parent;
					parent = (child - 1) / 2;
				}
				else
				{
					break;
				}
			}

		}

		void Adjust_down(size_t parent)
		{
			Compare com;
			size_t child = parent * 2 + 1;
			while (child < _con.size())
			{
				// 选出左右孩子中大的那一个
				//if (child+1 < _con.size() && _con[child+1] > _con[child])
				//if (child + 1 < _con.size() && _con[child] < _con[child + 1])
				if (child + 1 < _con.size() && com(_con[child], _con[child + 1]))
				{
					++child;
				}

				//if (_con[child] > _con[parent])
				//if (_con[parent] < _con[child])
				if (com(_con[parent], _con[child]))
				{
					std::swap(_con[child], _con[parent]);
					parent = child;
					child = parent * 2 + 1;
				}
				else
				{
					break;
				}
			}
		}

		void push(const T& val)
		{
			_con.push_back(val);
			Adjust_up(_con.size()-1);//调堆
		}

		void pop()
		{
			std::swap(_con[0], _con[_con.size() - 1]);
			_con.pop_back();
			Adjust_down(0);
		}

		const T& top()const
		{
			return _con[0];
		}

		bool empty()
		{
			return (_con.size() == 0);
		}

		bool empty() const 
		{
			return (_con.size()==0);
		}

	private:
		Container _con;//容器
	};

	void test()
	{
		priority_queue<int,vector<int>,greater<int>>pq;
		pq.push(1);
		pq.push(2);
		pq.push(3);
		pq.push(4);
		pq.push(6);
		pq.push(6);
		pq.push(5);
		pq.push(6);
		while (!pq.empty())
		{
			cout << pq.top()<<" ";
			pq.pop();
		}
		cout << endl;
		int arr[] = { 9,2,5,7,1,8,2,3,6,7,8,9,12,15,19,21 };
		priority_queue<int,vector<int>,greater<int>>p(arr, arr + sizeof(arr) / sizeof(arr[0]));
		while (!p.empty())
		{
			cout << p.top() << " ";
			p.pop();
		}

	}
}