C program that shows insertion operation in an AVL tree

#include <stdio.h>
typedef enum { FALSE ,TRUE } bool;
struct node
{
int val;
int balance;
struct node *left_child;
struct node *right_child;
};
struct node* search(struct node *ptr, int data)
{
if(ptr!=NULL)
  if(data < ptr -> val)
ptr = search(ptr -> left_child,data);
else if( data > ptr -> val)
ptr = search(ptr -> right_child, data);
return(ptr);
}
struct node *insert (int data, struct node *ptr, int *ht_inc)
{
struct node *aptr;

struct node *bptr;
if(ptr==NULL)
{
ptr = (struct node *) malloc(sizeof(struct node));
ptr -> val = data;
ptr -> left_child = NULL;
ptr -> right_child = NULL;
ptr -> balance = 0;
*ht_inc = TRUE;
return (ptr);
}
if(data < ptr -> val)
{
ptr -> left_child = insert(data, ptr -> left_child, ht_inc);
if(*ht_inc==TRUE)
 {
  switch(ptr -> balance)
 {
case -1: /* Right heavy */
ptr -> balance = 0;
*ht_inc = FALSE;
break;
case 0: /* Balanced */
ptr -> balance = 1;
break;
case 1: /* Left heavy */
aptr = ptr -> left_child;
if(aptr -> balance == 1)
 {
printf(“Left to Left Rotation\n”);
ptr -> left_child= aptr -> right_child;
aptr -> right_child = ptr;
ptr -> balance = 0;
aptr -> balance=0;
ptr = aptr;
 }
else
 {
printf(“Left to right rotation\n”);
bptr = aptr -> right_child;
aptr -> right_child = bptr -> left_child;
bptr -> left_child = aptr;
ptr -> left_child = bptr -> right_child;
bptr -> right_child = ptr;
if(bptr -> balance == 1 )
ptr -> balance = -1;
else
ptr -> balance = 0;
if(bptr -> balance == -1)
aptr -> balance = 1;
else
aptr -> balance = 0;
bptr -> balance=0;
ptr = bptr;
 }
*ht_inc = FALSE;
 }
 }
}
if(data > ptr -> val)

{
ptr -> right_child = insert(info, ptr -> right_child, ht_inc);
if(*ht_inc==TRUE)
 {
switch(ptr -> balance)
 {
case 1: /* Left heavy */
ptr -> balance = 0;
*ht_inc = FALSE;
break;
case 0: /* Balanced */
ptr -> balance = -1;
break;
case -1: /* Right heavy */
aptr = ptr -> right_child;
if(aptr -> balance == -1)
 {
printf(“Right to Right Rotation\n”);
ptr -> right_child= aptr -> left_child;
aptr -> left_child = ptr;
ptr -> balance = 0;
aptr -> balance=0;
ptr = aptr;
 }
else
 {
printf(“Right to Left Rotation\n”);
bptr = aptr -> left_child;
aptr -> left_child = bptr -> right_child;
bptr -> right_child = aptr;
ptr -> right_child = bptr -> left_child;
bptr -> left_child = pptr;
if(bptr -> balance == -1)
ptr -> balance = 1;
else
ptr -> balance = 0;
if(bptr -> balance == 1)
aptr -> balance = -1;
else
aptr -> balance = 0;
bptr -> balance=0;
ptr = bptr;
}/*End of else*/
*ht_inc = FALSE;
 }
 }
}
return(ptr);
}
void display(struct node *ptr, int level)
{
int i;
if ( ptr!=NULL )
{
display(ptr -> right_child, level+1);
printf(“\n”);
for (i = 0; i < level; i++)
printf(“ “);
printf(“%d”, ptr -> val);
display(ptr -> left_child, level+1);

}
}
void inorder(struct node *ptr)
{
if(ptr!=NULL)
{
inorder(ptr -> left_child);
printf(“%d “,ptr -> val);
inorder(ptr -> right_child);
}
}
main()
{
bool ht_inc;
int data ;
int option;
struct node *root = (struct node *)malloc(sizeof(struct node));
root = NULL;
while(1)
{
printf(“1.Insert\n”);
printf(“2.Display\n”);
printf(“3.Quit\n”);
printf(“Enter your option : “);
scanf(“%d”,&option);
switch(choice)
 {
  case 1:
printf(“Enter the value to be inserted : “);
scanf(“%d”, &data);
if( search(root,data) == NULL )
root = insert(data, root, &ht_inc);
else
printf(“Duplicate value ignored\n”);
 break;
  case 2:
if(root==NULL)
 {
printf(“Tree is empty\n”);
continue;
 }
printf(“Tree is :\n”);
display(root, 1);
printf(“\n\n”);
printf(“Inorder Traversal is: “);
inorder(root);
printf(“\n”);
break;
case 3:
exit(1);
default:
printf(“Wrong option\n”);
 }
 }
}