Program for insertion and deletion in heap.

# include <stdio.h>
int arr[100],n;
main()
{
int choice,num;
n=0;/*Represents number of nodes in the heap*/
while(1)
{
printf("1.Insert\n");
printf("2.Delete\n");
printf("3.Display\n");
printf("4.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("Enter the number to be inserted : ");
scanf("%d",&num);
insert(num,n);
n=n+1;
break;
case 2:
printf("Enter the number to be deleted : ");
scanf("%d",&num);
del(num);
break;
case 3:
display();
break;
case 4:
exit();
default:
printf("Wrong choice\n");
}/*End of switch */
}/*End of while */
}/*End of main()*/

display()
{       int i;
if(n==0)
{
printf("Heap is empty\n");
return;
}
for(i=0;i<n;i++)
printf("%d ",arr[i]);
printf("\n");
}/*End of display()*/

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;
}/*End of while*/
arr[0]=num; /*assign num to the root node */
}/*End of insert()*/

del(int num)
{
int left,right,i,temp,par;

for(i=0;i<n;i++)
{
if(num==arr[i])
break;
}
if( num!=arr[i] )
{
printf("%d not found in heap\n",num);
return;
}
arr[i]=arr[n-1];
n=n-1;
par=(i-1)/2;   /*find parent of node i */
if(arr[i] > arr[par])
{
insert( arr[i],i);
return;
}
left=2*i+1;  /*left child of i*/
right=2*i+2; /* right child of i*/
while(right < n)
{
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;
}/*End of while*/
if( left==n-1 && arr[i]<arr[left] ) /* right==n */
{    temp=arr[i];
arr[i]=arr[left];
arr[left]=temp;
}
}/*End of del()*/
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