C program to sort an array using heap sort

#include <stdio.h>
#define N 100
void heapsort(int [],int);
void heapify(int [],int,int);
main()
{
int i,n;
int a[N];
printf("Enter the size of the array\n");
scanf("%d",&n);
printf("Enter the numbers...\n");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
heapsort(a,n);
printf("\nSorted array is:\n");
for(i=0;i<n;i++)
{
printf("\n%2d",a[i]);
}
}
void heapify(int a[],int n,int i)
{
int largest=i,l,r,t;
l=2*i+1;
r=2*i+2;
if(l<n && a[l]>a[largest])
{
largest=l;
}
if(r<n && a[r]>a[largest])
{
largest=r;
}
if(largest!=i)
{
t=a[i];
a[i]=a[largest];
a[largest]=t;
heapify(a,n,largest);
}
}
void heapsort(int a[],int n)
{
int i,t;
for(i=n/2;i>=0;i--)
{
heapify(a,n,i);
}
for(i=n-1;i>=0;i--)
{
t=a[0];
a[0]=a[i];
a[i]=t;
heapify(a,i,0);
}
}