BST

#include<stdio.h>
#include<stdlib.h>
typedef struct node * BST;
struct node
{
  struct node *leftChild;
  int data;
  struct node *rightChild;
};
BST temp=NULL, ptr=NULL, root=NULL, prev=NULL;
BST newNode()
{
  BST X;
  X=(struct node *)malloc(sizeof(struct node));
  X->leftChild=X->rightChild=NULL;
  return X;
}
void createBST(int elem)
{
  temp=newNode();
  temp->data=elem;
  if(!root)
    root=temp;
  else
  {
    prev=NULL;
    ptr=root;
    while(ptr)
    {
      prev=ptr;
      ptr=(ptr->data<temp->data)?ptr->rightChild:ptr->leftChild;
      if(prev->data==elem) // remove duplicate entries
      {
        free(temp);
        return;
      }
    }
    if(prev->data<temp->data)
      prev->rightChild=temp;
    else if(prev->data>temp->data)
      prev->leftChild=temp;
  }
}
void inOrder(BST ptr)
{
  if(ptr)
  {
    inOrder(ptr->leftChild);
    printf("%d ",ptr->data);
    inOrder(ptr->rightChild);
  }
}
void preOrder(BST ptr)
{
  if(ptr)
  {
    printf("%d ",ptr->data);
    preOrder(ptr->leftChild);
    preOrder(ptr->rightChild);
  }
}
void postOrder(BST ptr)
{
  if(ptr)
  {
    postOrder(ptr->leftChild);
    postOrder(ptr->rightChild);
    printf("%d ",ptr->data);
  }
}
void traverBST()
{
  if(!root)
  {
    printf("\nThe Binary Search Tree is empty\n");
    return;
  }
  printf("\nThe inorder traversal of the entered BST is: ");
  inOrder(root);
  printf("\nThe preorder traversal of the entered BST is: ");
  preOrder(root);
  printf("\nThe postorder traversal of the entered BST is: ");
  postOrder(root);
  printf("\n");
}
void searchBST()
{
  if(!root)
  {
    printf("\nThe Binary Search Tree is empty\n");
    return;
  }
  int KEY;
  printf("\nEnter the KEY Element to be searched: ");
  scanf("%d",&KEY);
  ptr=root;
  while(ptr)
  {
    if(ptr->data==KEY)
    {
      printf("\nThe KEY %d is present in the entered BST\n",KEY);
      return;
    }
    ptr=(ptr->data<KEY)?ptr->rightChild:ptr->leftChild;
  }
  printf("\nThe KEY %d is not present in the enterd BST\n",KEY);
}
void exitProgram()
{
  printf("\nThank you for using the program");
  exit(0);
}
int main()
{
  int choice;
  while(1)
  {
    printf("\nPick a Binary Search Tree operation\n1) Create a Binary Search Tree\n2) Traverse the Binary Search Tree\n3) Seach for a KEY element in the Binary Search Tree\n4) Exit\n>| ");
    scanf("%d",&choice);
    switch(choice)
    {
      case 1:
      {
        int num,elem;
        printf("\nEnter the number of elements to be inserted into the Binary Search Tree: ");
        scanf("%d",&num);
        printf("\nEnter the elements to be inserted into the Binary Search Tree: ");
        for(int i=1;i<=num;i++)
        {
          scanf("%d",&elem);
          createBST(elem);
        }
      }
      break;
      case 2:
        traverBST();
      break;
      case 3:
        searchBST();
      break;
      case 4:
        exitProgram();
      break;
      default:
        printf("\nInvalid Choice\n");
      }
    }
    return 0;
}