堆排序中构造最大堆C/C++

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在堆排序算法中，我们使用的是最大堆。下面的代码是给定一组数，构造一个最大堆。left(heap, location)和right(heap, location)分别返回数组heap中location的左右孩子的索引。max_heapify(heap, i)是确保heap数组的i的左右孩子都满足最大堆化。bulid_max_heap(heap)将heap数组构造一个最大堆。

/*构造一个NUM个数最大堆；*/#include<iostream>#include<ctime>using namespace std;const int NUM = 10;void print(int p[] , int n){for (int i = 1; i <= n; i++){cout << "heap[" << i << "] = " << p[i] << endl;}}int left(int heap[] , int i){return 2 * i;}int right(int heap[] , int i){return 2 * i + 1;}void max_heapify(int heap[], int location){int largest = 0, l, r, temp;l = left(heap, location);r = right(heap, location);if (l <= NUM && heap[l] > heap[location]){largest = l;}elselargest = location;if (r <= NUM && heap[r] > heap[largest]){largest = r;}if (location != largest){temp = heap[location];heap[location] = heap[largest];heap[largest] = temp;max_heapify(heap, largest);}}void bulid_max_heap(int heap[]){//叶子节点不用max_heapify，所以是节点数的一半for (int i = NUM / 2; i >= 1; i--){max_heapify(heap, i);}}int main(){int heap[NUM + 1] = {0};srand(time(NULL));for (int i = 1; i <= NUM; i++){heap[i] = rand() % 100;}print(heap, NUM);bulid_max_heap(heap);cout << "-------------" << endl;print(heap, NUM);return 0;}

结果如下：

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