目录

仿函数

模拟实现

结果

大根堆

小根堆

完整代码

priority_queue.h

test.c

---

仿函数

仿函数的通俗定义：仿函数（functor）又称为函数对象（function object）是一个能行使函数功能

的类。仿函数的语法几乎和我们普通的函数调用一样，不过作为仿函数的类，都必须重operator()

运算符

模拟实现

结果

大根堆

小根堆

完整代码

priority_queue.h

#pragma once

template<class T,class Contianer=vector<T>,class Compare=Less<T>>
class priority_queue
{
public:
	priority_queue()
	{ }

    void adjust_up(int child)
    {
        int parent = (child - 1) / 2;
        while (child > 0)
        {
            if (com(_con[parent], _con[child]))
            {
                swap(_con[parent], _con[child]);
                child = parent;
                parent = (child - 1) / 2;
            }
            else
            {
                break;
            }
        }
    }

    void adjust_down(int parent)
    {
        int child = parent * 2 + 1;
        while (child < _con.size())
        {
            if (child + 1 < _con.size() && com(_con[child], _con[child + 1]))
            {
                ++child;
            }
            if (com(_con[parent], _con[child]))
            {
                swap(_con[parent], _con[child]);
                parent = child;
                child = parent * 2 + 1;
            }
            else
            {
                break;
            }
        }
    }

    template <class InputIterator>
    priority_queue(InputIterator first, InputIterator last)
        :_con(first, last)
    {
        for (int i = (_con.size() - 2) / 2; i >= 0; i--)
        {
            adjustup(i);
        }
    }

    bool empty() const
    {
        return _con.empty();
    }

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

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

    void push(const T& x)
    {
        _con.push_back(x);
        adjust_up(_con.size() - 1);
    }

    void pop()
    {
        swap(_con[0], _con[_con.size() - 1]);
        _con.pop_back();
        adjust_down(0);
    }
private:
	Contianer _con;

	Compare com;
};

test.c

#define _CRT_SECURE_NO_WARNINGS 1

#include <iostream>
#include <vector>

using namespace std;

#include "priority_queue.h"

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

template<class T>
class Greater
{
public:
	bool operator()(const T& x, const T& y)
	{
		return x > y;
	}
};

void test()
{
	priority_queue<int> q;
	q.push(1);
	q.push(2);
	q.push(3);
	q.push(4);
	q.push(5);

	while (!q.empty())
	{
		cout << q.top() << ' ';
		q.pop();
	}
	cout << endl;
}

int main()
{
	test();
	return 0;
}