数据结构-堆排序

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堆排序（Heapsort）是指利用堆这种数据结构所设计的一种排序算法。堆是一个近似完全二叉树的结构，并同时满足堆性质：即子结点的键值或索引总是小于（或者大于）它的父节点。

#pragma once #include<vector>#include<assert.h>template<class T>class Heap{public:Heap():_a(NULL){}Heap(const T* a, int size){_a.reserve(size);for (int i = 0; i < size; i++){_a.push_back(a[i]);}size_t parent = (size - 2) / 2;for (int i = (_a.size() - 2) / 2; i >= 0; --i){_AdjustDown(i, size);}}~Heap(){}//堆排序//将数据从小到大输出，void HeapSort(T*  a,int  size){while (size > 1){swap(_a[0], _a[size - 1]);size--;_AdjustDown(0, size);}}void Print( size_t size){for (int i = 0; i < size; i++){cout << _a[i] << "  ";}cout << endl;}protected:void _AdjustDown(size_t parent, size_t size){size_t child = parent * 2 + 1;while (child<size){if (child + 1<size &&_a[child]<_a[child + 1]){++child;}if (_a[child] > _a[parent]){swap(_a[child], _a[parent]);parent = child;child = parent * 2 + 1;}elsebreak;}}protected:vector<T>  _a;};void Test(){int array[] = { 10, 11, 13, 12, 19,16, 18, 15, 17, 14  };Heap<int> hp1(array, sizeof(array) / sizeof(array[0]));hp1.HeapSort(array, sizeof(array) / sizeof(array[0]));hp1.Print(sizeof(array) / sizeof(array[0]));}

//堆排序#include<iostream>using namespace std;#include<assert.h>void AdjustDown(int* a, size_t size, size_t parent){int child = parent * 2 + 1;  //给出父节点可以求出子节点，parent*2+1while (child < size)//不能等于，child=*2+1，可能等于size{if (child + 1 < size && a[child + 1] > a[child])//比较左右孩子那个大{++child;//如果a[child+1]大，下标++，指向child+1}if (a[child] > a[parent])  //如果子节点比父节点大，就交换，父节点变为大的{swap(a[child], a[parent]);parent = child;//向下继续调整，child赋值给parentchild = parent * 2 + 1;}else{break;}}}void HeapSort(int* a, size_t size){assert(a);// 建堆 N*Lg(N)for (int i = (size - 2) / 2; i >= 0; --i) //从父节点开始进行调整{//i-1为最后一个元素下标，在减一除以2求出父节点的下标AdjustDown(a, size, i);//}for (int i = 0; i < size; ++i){swap(a[0], a[size - 1 - i]);//此时a[0]存放最大数字，和最后进行交换//最大的就跑到最后面，再以0为父节点，size-1-i个数据进行调整。AdjustDown(a, size - 1 - i, 0);}}void PrintArray(int* a, int n){for (int i = 0; i < n; i++){cout << a[i] << " ";}cout << endl;}void TestHeapSort(){//int a[] = { 2, 5, 4, 6, 8, 0 };int a[] = { 2, 5, 4, 9, 3, 6, 8, 7, 1, 0 };HeapSort(a, sizeof(a) / sizeof(a[0]));PrintArray(a, sizeof(a) / sizeof(a[0]));}int main(){TestHeapSort();system("pause");return 0;}

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