Heap Sort in C++

#include <stdio.h>


void swap(int arr[], const int a, const int b) {
   int tmp = arr[a];
   arr[a] = arr[b];
   arr[b] = tmp;
}

void heapify(int arr[], const int size, const int i) {
   int largest = i;
   int leftLeaf = 2*i + 1;
   int rightLeaf = 2*i + 2;

   if(leftLeaf < size && arr[leftLeaf] > arr[largest]) {
       largest = leftLeaf;
   }

   if(rightLeaf < size && arr[rightLeaf] > arr[largest]) {
       largest = rightLeaf;
   }

   if(largest != i) {
       swap(arr, i, largest);
       heapify(arr, size, largest);
   }
}

void sort(int arr[], const int size) {

   for(int i = (int)(size / 2 - 1); i >= 0; --i) {
       heapify(arr, size, i);
   }

   int j = size - 1;
   while(j >= 1) {
       swap(arr, 0, j);
       heapify(arr,j,0);
       --j;
   }
}

// Demo:
int main() {
   // Test array:
   int a[] = {4, 8, 5, 1, 2, 0, 9};
   // Get the number of elements in the array:
   int s = sizeof(a) / sizeof(a[0]);

   // Sort the array:
   sort(a, s);

   for(int i = 0; i < s; ++i) {
       printf("%d ", a[i]);
   }
   printf("\n");

   return 0;
}