堆排序

#include "stdafx.h"void MAX_HEAPIFY(int a[], int i, int len){    int l = 2 * i + 1, r = 2 * i + 2;    int largest = i;                                             //预设该节点为最大    if (l <= len &&a[l] > a[i])    {        largest = l;    }    if (r <= len &&a[r] > a[largest])    {        largest = r;    }    if (largest != i)    {        int temp = a[i];        a[i] = a[largest];        a[largest] = temp;        MAX_HEAPIFY(a, largest, len);    }}void BUILD_MAX_HEAO(int a[], int len){    for (int i = len / 2; i > -1; --i)    {        MAX_HEAPIFY(a, i, len);                                        //从下往上，保证每个都是最大堆    }}void HEAP_SORT(int a[],int len){    BUILD_MAX_HEAO(a,len);    int len2 = len;    for (int i = len; i > 0;--i)    {        int temp = a[0];        a[0] = a[i];        a[i] = temp;        --len2;                                                       //构建最大堆时排除最后一个节点        MAX_HEAPIFY(a, 0, len2);    }}int _tmain(int argc, _TCHAR* argv[]){    int a[] = { 27, 17, 3, 16, 13, 10, 1, 5, 7, 12, 4, 8, 9, 0 };    int len = sizeof(a) / 4 - 1;    HEAP_SORT(a, len);    for (int i = 0; i < len + 1; ++i)    {        cout << a[i] << endl;    }    return 0;}