C Program For Insertion And Deletion In Heap

C program code for Insertion and Deletion in a Heap.

#include <stdio.h>
#include<stdlib.h>
int arr[100],n;
void display();
void insert(int num,int loc);
void del(int num);

void main()
 {
 int choice,num;
 n=0; //number of nodes in the heap
 while(1) //loop for menu
  {
  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(0);
   default: printf("Wrong choice\n");
   }
  }
 }

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

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; //assign num to the root node
 }

void 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;
  }
 if( left==n-1 && arr[i]<arr[left] ) /* right==n */
  {
  temp=arr[i];
  arr[i]=arr[left];
  arr[left]=temp;
  }
 }