C program for heap sorting

/* Program of sorting through heapsort*/

# include <stdio.h>

void display();

void del_root(int last);

void create_heap();

void heap_sort();

void insert(int num,int loc);

int arr[20],n;

void main()

{
    int i;

    printf("Enter number of elements : ");

      scanf("%d",&n);

    for(i=0;i<n;i++)

       {
           printf("Enter element %d : ",i+1);

              scanf("%d",&arr[i]);

        }
     printf("Entered list is :\n");

       display();


       create_heap();


     printf("Heap is :\n");

       display();


     heap_sort();


     printf("Sorted list is :\n");

         display();

}

void display()

   {     
       int i;


   for(i=0;i<n;i++)

         printf("%d  ",arr[i]);


 printf("\n");


  }

void create_heap()

    {
        int i;

     for(i=0;i<n;i++)


         insert(arr[i],i) ;
    }

 void insert(int num,int loc)

      {
          int par ;

   while(loc>0)

       {

              par=(loc-1)/2;

           if(num<=arr[par])

             {

               arr[loc]=num;

                return;
             }

             arr[loc]=arr[par];

            loc=par;
      }


         arr[0]=num;

  }

void heap_sort()

     {
          int last;

  for(last=n-1; last>0; last--)

         del_root(last);

     }

  void del_root(int last)

        {
            int left,right,i,temp;

            i=0; /*Since every time we have to replace root with last*/
 /*Exchange last element with the root */

         temp=arr[i];

         arr[i]=arr[last];

         arr[last]=temp;

        left=2*i+1;   /*left child of root*/

        right=2*i+2;  /*right child of root*/

        while( right < last)

           {
               
   if( arr[i]>=arr[left] && arr[i]>=arr[right] )

                  return;

               if( arr[right]<=arr[left] )

                 {
                    temp=arr[i];

                    arr[i]=arr[left];

                    arr[left]=temp;

                    i=left;
                 }
             else

                {
                   temp=arr[i];

                   arr[i]=arr[right];

                   arr[right]=temp;

                    i=right;
                }

         left=2*i+1;

         right=2*i+2;

      }

                
 if( left==last-1 && arr[i]<arr[left] )/*right==last*/

              {
                     temp=arr[i];

                     arr[i]=arr[left];

                     arr[left]=temp;
               }


         }       /  *End of del_root*/














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