TheAlgorithms-C/sorting/Heap_Sort.c

#include <stdio.h>

void max_heapify(int* a, int i, int n);
void heapsort(int* a, int n);
void build_maxheap(int* a, int n);

void max_heapify(int* a, int i, int n) {
  int j, temp;
  temp = a[i];
  j = 2 * i;
  while (j <= n) {
    if (j < n && a[j + 1] > a[j])
      j = j + 1;
    if (temp > a[j]) {
      break;
    } else if (temp <= a[j]) {
      a[j / 2] = a[j];
      j = 2 * j;
    }
  }
  a[j / 2] = temp;
  return;
}

void heapsort(int* a, int n) {
  int i, temp;
  for (i = n; i >= 2; i--) {
    temp = a[i];
    a[i] = a[1];
    a[1] = temp;
    max_heapify(a, 1, i - 1);
  }
}

void build_maxheap(int* a, int n) {
  int i;
  for (i = n / 2; i >= 1; i--) {
    max_heapify(a, i, n);
  }
}

int main() {
  int n, i;
  printf("Enter number of elements of array\n");
  scanf("%d", &n);
  int a[20];
  for (i = 1; i <= n; i++) {
    printf("Enter Element %d\n", i);
    scanf("%d", a + i);
  }

  build_maxheap(a, n);
  heapsort(a, n);
  printf("Sorted Output\n");
  for (i = 1; i <= n; i++) {
    printf("%d\n", a[i]);
  }

  getchar();
}