Programming Practice: In-Place Heap Sort In C

gistfile1.c

#include <cstdio>
#include <ctime>
#include <cstdlib>

void make_heap(int * a, size_t n) {
	for(int heapsize = 0; heapsize < n; ++heapsize) {
		int n = heapsize;
		while(n > 0) {
			int p = (n-1) / 2;
			if (a[n] > a[p]) {
				int t = a[n];
				a[n] = a[p];
				a[p] = t;
				n = p;
			} else break;
		}
	}
}

void sort_heap(int * a, size_t n) {
	int heapsize = n; 
	while(heapsize > 0) {
		int t = a[0];
		a[0] = a[--heapsize];
		a[heapsize] = t;
		int p = 0;
		int c = 1;
		while(c < heapsize) {
			if (c + 1 < heapsize && a[c + 1] > a[c]) c++;
			if (a[c] > a[p]) {
				int t = a[p];
				a[p] = a[c];
				a[c] = t;
				p = c;
				c = p * 2 + 1;
			} else {
				break;
			}
		}
	}
}


int main() {

	int a[30];
	srand(time(0));
	for (int i = 0; i < 30; ++i) 
		a[i] = rand() % 100;

	make_heap(a, 30);
	sort_heap(a, 30);

	printf("array: ");
	for(int i = 0; i < 30; ++i)
		printf("%d ", a[i]);
	printf("\n");

	return 0;
}