updated documentation and format

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#include<stdio.h>
#include<stdlib.h>
/**
* @file
* \brief Threaded Binary Tree is a binary tree variant in which all left child
* pointers that are NULL (in Linked list representation) point to its
* in-order predecessor, and all right child pointers that are NULL
* (in Linked list representation) point to its in-order successor.
* This file is a simple implementation of a Threaded Binary Tree
* with the following functionalities:
* - Insertion
* - Search
* - Deletion
* - Listing of node keys inorder,preorder,postorder
* \author [Amitha Nayak](https://github.com/amitnayakblr)
*/
/*Threaded Binary Tree is a binary tree variant in which all left child
pointers that are NULL (in Linked list representation) point to its
in-order predecessor, and all right child pointers that are NULL
(in Linked list representation) point to its in-order successor.
#include <stdio.h>
#include <stdlib.h>
This file is a simple implementation of a Threaded Binary Tree
with the following functionalities:
- Insertion
- Search
- Deletion
- Listing of node keys inorder,preorder, postorder
*/
/**
* Node, the basic data structure of the tree
**/
typedef struct Node {
int data; /**< stores the number */
struct Node *llink; /**< link to left child */
struct Node *rlink; /**< link to right child */
} node;
// Node, the basic data structure in the tree
typedef struct Node
{
int data;
struct Node *llink;
struct Node *rlink;
}node;
node* create_node(int data)
{
node *ptr=(node*) malloc(sizeof(node));
ptr->rlink=ptr->llink=NULL;
ptr->data=data;
return ptr;
/**
* creates a new node
* param[in] data value to be inserted
* \returns a pointer to the new node
**/
node *create_node(int data) {
node *ptr = (node *)malloc(sizeof(node));
ptr->rlink = ptr->llink = NULL;
ptr->data = data;
return ptr;
}
void insert_BT(node **root,int data)
{
node *new_node=create_node(data);
node *temp; //to be deleted
node *prev; //keeps track of the parent of the element deleted
if(*root==NULL)
{
*root=new_node;
}
else
{
temp=*root;
prev=NULL;
while(temp!=NULL)
{
if(new_node->data>temp->data)
{
prev=temp;
temp=temp->rlink;
}
else if(new_node->data<temp->data)
{
prev=temp;
temp=temp->llink;
}
else
{
return;
}
}
/**
* inserts a node into the tree
* param[in,out] root pointer to node pointer to the topmost node of the tree
* param[in] data value to be inserted into the tree
*/
void insert_BT(node **root, int data) {
node *new_node = create_node(data);
node *temp; // to be deleted
node *prev; // keeps track of the parent of the element deleted
if (*root == NULL) {
*root = new_node;
} else {
temp = *root;
prev = NULL;
while (temp != NULL) {
if (new_node->data > temp->data) {
prev = temp;
temp = temp->rlink;
} else if (new_node->data < temp->data) {
prev = temp;
temp = temp->llink;
} else {
return;
}
}
if(new_node->data>prev->data)
{
prev->rlink=new_node;
}
else
{
prev->llink=new_node;
}
}
if (new_node->data > prev->data) {
prev->rlink = new_node;
} else {
prev->llink = new_node;
}
}
}
// returns "Element found" if the search element is present else returns, "Element not found"
void search(node *root, int ele)
{
node *temp=root;
while(temp!=NULL)
{
if(temp->data==ele)
{
break;
}
else if(ele>temp->data)
{
temp=temp->rlink;
}
else
{
temp=temp->llink;
}
}
/**
* searches for the element
* \param[in] root node pointer to the topmost node of the tree
* \param[in] ele value searched for
*/
void search(node *root, int ele) {
node *temp = root;
while (temp != NULL) {
if (temp->data == ele) {
break;
} else if (ele > temp->data) {
temp = temp->rlink;
} else {
temp = temp->llink;
}
}
if(temp==NULL)
{
printf("%s\n","Element not found." );
}
else printf("%s\n","Element found." );
if (temp == NULL) {
printf("%s\n", "Element not found.");
} else
printf("%s\n", "Element found.");
}
void inorder_display(node *curr)
{
if(curr!=NULL)
{
inorder_display(curr->llink);
printf("%d\t",curr->data );
inorder_display(curr->rlink);
}
/*
* performs inorder traversal
* param[in] curr node pointer to the topmost node of the tree
*/
void inorder_display(node *curr) {
if (curr != NULL) {
inorder_display(curr->llink);
printf("%d\t", curr->data);
inorder_display(curr->rlink);
}
}
void postorder_BT(node *curr)
{
if(curr!=NULL)
{
postorder_BT(curr->llink);
postorder_BT(curr->rlink);
printf("%d\t",curr->data);
}
/*
* performs postorder traversal
* param[in] curr node pointer to the topmost node of the tree
*/
void postorder_BT(node *curr) {
if (curr != NULL) {
postorder_BT(curr->llink);
postorder_BT(curr->rlink);
printf("%d\t", curr->data);
}
}
void preorder_BT(node *curr)
{
if(curr!=NULL)
{
printf("%d\t",curr->data);
preorder_BT(curr->llink);
preorder_BT(curr->rlink);
}
/*
* performs preorder traversal
* param[in] curr node pointer to the topmost node of the tree
*/
void preorder_BT(node *curr) {
if (curr != NULL) {
printf("%d\t", curr->data);
preorder_BT(curr->llink);
preorder_BT(curr->rlink);
}
}
// deletes the node if present, else it takes no action.
void delete_BT(node **root,int ele)
{
node* temp;
node *prev;
if(*root==NULL) return;
else
{
temp=*root;
prev=NULL;
// search
while(temp!=NULL)
{
if(temp->data==ele)
{
break;
}
else if(ele>temp->data)
{
prev=temp;
temp=temp->rlink;
}
else
{
prev=temp;
temp=temp->llink;
}
}
}
/*
* deletion of a node from the tree
* if the node isn't present in the tree, it takes no action.
* param[in,out] root pointer to node pointer to the topmost node of the tree
* param[in] ele value to be deleted from the tree
*/
void delete_BT(node **root, int ele) {
node *temp;
node *prev;
if (*root == NULL)
return;
else {
temp = *root;
prev = NULL;
// search
while (temp != NULL) {
if (temp->data == ele) {
break;
} else if (ele > temp->data) {
prev = temp;
temp = temp->rlink;
} else {
prev = temp;
temp = temp->llink;
}
}
}
if(temp==NULL)
return;
else
{
node *replacement; //deleted node's replacement
node *t;
if(temp->llink==NULL && temp->rlink==NULL)
{
replacement=NULL;
}
else if(temp->llink==NULL && temp->rlink!=NULL)
{
replacement=temp->rlink;
}
else if(temp->llink!=NULL && temp->rlink==NULL)
{
replacement=temp->llink;
}
else
{
replacement=temp->rlink; //replaced with inorder successor
t=replacement;
while(t->llink!=NULL)
{
t=t->llink;
}
t->llink=temp->llink; //leftmost node of the replacement is linked to the left child of the deleted node
}
if (temp == NULL)
return;
else {
node *replacement; // deleted node's replacement
node *t;
if (temp->llink == NULL && temp->rlink == NULL) {
replacement = NULL;
} else if (temp->llink == NULL && temp->rlink != NULL) {
replacement = temp->rlink;
} else if (temp->llink != NULL && temp->rlink == NULL) {
replacement = temp->llink;
} else {
replacement = temp->rlink; // replaced with inorder successor
t = replacement;
while (t->llink != NULL) {
t = t->llink;
}
t->llink = temp->llink; // leftmost node of the replacement is linked to
// the left child of the deleted node
}
if(temp==*root)
{
free(*root);
*root=replacement;
}
else if(prev->llink==temp)
{
free(prev->llink);
prev->llink=replacement;
}
else if(prev->rlink==temp)
{
free(prev->rlink);
prev->rlink=replacement;
}
}
}
void main()
{
printf("BINARY TREE: \n");
node *root=NULL;
int choice,n;
do
{
printf("%s\n","1. Insert into BT" );
printf("%s\n","2. Print BT - inorder" );
printf("%s\n","3. Print BT - preorder" );
printf("%s\n","4. print BT - postorder" );
printf("%s\n","5. delete from BT" );
printf("%s\n","6. search in BT" );
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("%s\n","Enter a no:" );
scanf("%d",&n);
insert_BT(&root,n);
break;
case 2:
inorder_display(root);
printf("\n");
break;
case 3:
preorder_BT(root);
printf("\n");
break;
case 4:
postorder_BT(root);
printf("\n");
break;
case 5:
printf("%s\n","Enter a no:" );
scanf("%d",&n);
delete_BT(&root,n);
break;
case 6:
printf("%s\n","Enter a no:" );
scanf("%d",&n);
search(root,n);
break;
}
}while(choice!=0);
if (temp == *root) {
free(*root);
*root = replacement;
} else if (prev->llink == temp) {
free(prev->llink);
prev->llink = replacement;
} else if (prev->rlink == temp) {
free(prev->rlink);
prev->rlink = replacement;
}
}
}
/*
* main function
*/
void main() {
printf("BINARY THREADED TREE: \n");
node *root = NULL;
int choice, n;
do {
printf("%s\n", "1. Insert into BT");
printf("%s\n", "2. Print BT - inorder");
printf("%s\n", "3. Print BT - preorder");
printf("%s\n", "4. print BT - postorder");
printf("%s\n", "5. delete from BT");
printf("%s\n", "6. search in BT");
printf("%s\n", "Type 0 to exit");
scanf("%d", &choice);
switch (choice) {
case 1:
printf("%s\n", "Enter a no:");
scanf("%d", &n);
insert_BT(&root, n);
break;
case 2:
inorder_display(root);
printf("\n");
break;
case 3:
preorder_BT(root);
printf("\n");
break;
case 4:
postorder_BT(root);
printf("\n");
break;
case 5:
printf("%s\n", "Enter a no:");
scanf("%d", &n);
delete_BT(&root, n);
break;
case 6:
printf("%s\n", "Enter a no:");
scanf("%d", &n);
search(root, n);
break;
}
} while (choice != 0);
}