Heap

/* Program for sorting an array in
   ascending order using heap sort */
#include<stdio.h>

void create(int []);
void down_adjust(int [],int);

int main()
{ int heap[30],n,i,last,temp;
  printf("\nEnter no. of elements :");
  scanf("%d",&n);
  printf("\nEnter the data to be sort :");
  for(i=1;i<=n;i++)
    scanf("%d",&heap[i]);
  //create a heap
  heap[0]=n;
  create(heap);
  //sorting
  while(heap[0] > 1)
   {       //swap heap[1] and heap[last]
     last=heap[0];
     temp=heap[1];
     heap[1]=heap[last];
     heap[last]=temp;
     heap[0]--;
     down_adjust(heap,1);
   }
//print sorted data
 printf("\nsorted data is :\n");
 for(i=1;i<=n;i++)
    printf("%d   ",heap[i]);
}

void create(int heap[])
{ int i,n;n=heap[0]; //no. of elements
for(i=n/2;i>=1;i--)
  down_adjust(heap,i);
}

void down_adjust(int heap[],int i)
{       int j,temp,n,flag=1;
n=heap[0];
while(2*i<=n && flag==1)
{ j=2*i;  //j points to left child
if(j+1<=n && heap[j+1] > heap[j])
 j=j+1;
if(heap[i] > heap[j])
 flag=0;
else
{ temp=heap[i];
 heap[i]=heap[j];
 heap[j]=temp;
 i=j;
}
}
}
/*
---Output ---

Enter no. of elements :3
Enter the data to be sort :35
23
56
sorted data is :
23
35
56
*/