C++大小堆实现（仿函数）

具体代码如下

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

using namespace std;

template<class T>
class Big
{
public:
    bool operator()(T x, T y)
    {
        return x > y;
    }
};
template<class T=int>
class Sma
{
public:
    bool operator()(T x, T y)
    {
        return x < y;
    }
};

template<class T,class Cmp>
class Heap
{
public:
    Heap()
    {}
    Heap(const T* arr, size_t size)
    {
        for (int i = 0; i < size; ++i)
        {
            _heap.push_back(arr[i]);
        }
        int root = (_heap.size() - 2) / 2;//找到第一个非叶子结点
        while (root>=0)
            //向下调整
            AdjustDown(root--);
    }

    void Push(T & t)
    {
        _heap.push_back(t);
        AdjustUp(_heap.size() - 1);
    }
    void pop()
    {
        if (_heap.size() == 0)
            return;
        if (_heap.size() <= 2)
        {
            swap(_heap[0], _heap[_heap.size() - 1]);
            _heap.pop_back();
        }
        else
        {
            swap(_heap[0], _heap[_heap.size() - 1]);
            _heap.pop_back();
            AdjustDown(0);
        }
    }
    bool IsEmpty()const
    {
        return _heap.size() == 0;
    }
    const T & top() const
    {
        if (_heap.size() != 0)
            return _heap[0];
        else
            throw exception("this is a bug");
    }
protected:
    void AdjustDown(int root)
    {
        //int child = root * 2 + 2 >= _heap.size() ? root * 2 + 1 : Cmp(_heap[root * 2 + 1], _heap[root * 2 + 2]) ? root * 2 + 1 : root * 2 + 2;
        while (root <= (_heap.size() - 2) / 2)
        {
            int child = root * 2 + 2 >= _heap.size() ? root * 2 + 1 : Cmp()(_heap[root * 2 + 1], _heap[root * 2 + 2]) ? root * 2 + 1 : root * 2 + 2;
            if (!Cmp()(_heap[root], _heap[child]))
            {
                swap(_heap[root], _heap[child]);
            }
            else
            {
                break;
            }
            root = child;
        }
    }

    void AdjustUp(int child)
    {
        while (child >= 1)
        {
            int root = (child - 1) / 2;
            if (!Cmp()(_heap[root], _heap[child]))
            {
                swap(_heap[root], _heap[child]);
            }
            child = root;
        }
    }
protected:
    vector<T> _heap;
};


void test_heap()
{
    int arr[] = { 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 };
    Heap<int, Sma<int> >hp1(arr, 10);
    int b = 3;
    hp1.Push(b);
    cout << "Over!" << endl;
    while (!hp1.IsEmpty())
    {
        cout << hp1.top() << " ";
        hp1.pop();
    }
    system("pause");
}

原文链接: https://www.cnblogs.com/lang5230/p/5309220.html

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