Heap Sort - Algorithm

#include<stdlib.h>
#include<stdio.h>
#include<time.h>
#define s 10

long a[s];
long heapsize;
void max_heapify(long i){
    long largest;
    long l= 2*i+1;
    long  r=2*i+2 ;
    if (l< heapsize  && a[l] >a[i])
         largest =l;
    else
        largest =i;
    if (r< heapsize  && a[r] >a[largest])
         largest =r;
    if(largest !=i){
        long temp1= a[i];
        a[i]=a[largest];
        a[largest] = temp1;

        max_heapify(largest);}
}


void build_max_heap(){
     heapsize = s ;
    for(long i=(s/2)-1 ;i>=0; i--)
        max_heapify(i);
}
void heap_sort(){
    build_max_heap();

    for(long i=s-1; i>0 ;i--)
    {long temp2 = a[i];
    a[i]=a[0];
    a[0]=temp2;

    heapsize =heapsize -1;
    max_heapify(0);}
}

int main () {

    long i=0,j=0,temp;
    clock_t begin,end;
    double time_spent;
    srand(time(NULL));

    for(long i= 0; i<s; i++){
         a[i]= rand()%s;}

    begin = clock();
    heap_sort();
    end=clock();
    time_spent=(double)(end-begin);
    for(long i=0; i<s; i++){
          printf(" %d  ", a[i]);}
    printf("\nTime Elapsed:%f\n",time_spent);
    return 0;

}