Binary Tree in C is a non-linear data structure in which the node is linked to two successor nodes, namely root, left and right. In preorder traversal, we first visit the root and then the left subtree and lastly the right subtree. * C Program to Implement Binary Tree using Linked List, Prev - C Program to Display Floyd’s triangle, Next - C Program to Find Area of Trapezium, Java Programming Examples on Combinatorial Problems & Algorithms, Python Programming Examples on Searching and Sorting, Java Algorithms, Problems & Programming Examples, C Programming Examples on Combinatorial Problems & Algorithms, C++ Algorithms, Problems & Programming Examples, Java Programming Examples on Graph Problems & Algorithms, C Programming Examples on Graph Problems & Algorithms, C++ Programming Examples on Graph Problems & Algorithms, Java Programming Examples on Data-Structures, C++ Programming Examples on Data-Structures, C Programming Examples on Data-Structures, C Programming Examples without using Recursion, C# Programming Examples on Data Structures, Python Programming Examples on Linked Lists. There are three ways which we use to traverse a tree − In-order Traversal; Pre-order Traversal; Post-order Traversal; We shall now look at the implementation of tree traversal in C programming language here using the following binary tree − Implementation in C In postorder traversal, we first visit the left subtree and then the right and lastly the node. printf(" %c ", root->data) – We are first visiting the root (of the main tree or subtree) or the current node then we will visit its left subtree and then the right subtree. Now, we have made our node and a function to add new nodes. ‘get_height’ is the function to calculate the height of the tree. preorder(root->left_child) – Then we are visiting the left subtree. preorder(root->right_child) – And lastly the right subtree. Program to implement Binary Tree using the linked list Explanation. struct node *right_child – ‘right_child’ is a pointer to the node (our defined structure). This post is about implementing a binary tree in C. You can visit Binary Trees for the concepts behind binary trees. Inserting a new node in a linked list in C. 12 Creative CSS and JavaScript Text Typing Animations. Now, we have a structure of our node and we need a function to create new nodes to make a tree. Output: We will use linked representation to make a binary tree in C and then we will implement inorder, preorder and postorder traversals and then finish this post by making a function to calculate the height of the tree. If both the children of a node are null then it is a leaf node. This C Program implements binary tree using linked list. 2) Traverse the root. 3) Traverse the right subtree in preorder. Also, the height of a leaf node or a null node is 0. 2) Traverse the left subtree in preorder. This C Program implements binary tree using linked list. So, let’s write it. p = malloc(sizeof(struct node)) – We are allocating a space in the memory to the node and storing the address of the memory in the variable ‘p’. Traversal Algorithm: Preorder : 1) Traverse the root.  E  A  B  D  F  The C program is successfully compiled and run on a Linux system.  D  A  E  B  F  Thus, we will use this to link the current node with its right child. The binary tree we will be using in this post is: So, let’s make a node using a structure in C. char data – The data which we are going to store in this node is of character type. Sanfoundry Global Education & Learning Series – 1000 C Programs. This is called binary-search-tree property, If you wish to look at other example programs on Trees, go to. Now, we are ready to write a function to get the height of any node of tree. The tree can be traversed in in-order, pre-order or post-order. A complete binary tree can be represented in an array in the following approach. We are doing the same here. Thus, the next task is to allocate the memory to the node and we will do it using the malloc function. In both cases, the height will be 0. We first visit the left subtree and then root and lastly the right subtree in inorder traversal. All Rights Reserved. A typical binary tree can be represented as follows: In the binary tree, each node can have at most two children. p->right_child = NULL – Similarly, we also made the right child null. So, let’s first make the tree in the main function. Please note that we have just declared a node here and no memory has been yet assigned to store data. Functions and pseucodes Algorithm Begin Take the nodes of the tree as input. But, before we begin this tutorial, it is important to have a crystal clear understanding of pointers and linked lists in C. Each node can have zero, one or two children. We will use linked representation to make a binary tree in C and then we will implement inorder, preorder and postorder traversals and then finish this post by making a function to calculate the height of the tree. Binary Search tree is a binary tree in which each internal node x stores an element such that the element stored in the left subtree of x are less than or equal to x and elements stored in the right subtree of x are greater than or equal to x. We are first checking for a null node or leaf node with if(a==NULL || is_leaf(a)). ‘get_max’ is a function to determine the greater number of the two numbers passed to it. Let’s implement the above concepts and see the result. The following C program build a binary tree using linked list. © 2011-2020 Sanfoundry. struct node *left_child – Similarly, we will use this to link the current node with its left child. struct node *p – ‘*p’ is a node and ‘p’ is a pointer to the node. Binary trees are a very popular concept in the C programming language. Here’s the list of Best Reference Books in C Programming, Data-Structures and Algorithms, This C Program implements binary tree using linked list. Inorder: 1) Traverse the left subtree in inorder. Else, the height will be 1+maximum among the heights of left and the right subtrees – get_max(get_height(a->left_child), get_height(a->right_child)) + 1. Here, we are just storing data in it. The program output is also shown below. Here is a C++ program to Implement a Binary Search Tree using Linked Lists.  E  B  A  F  D  Thus, we first write a function to identify a leaf node. Thus, the next task is to make the tree described in the above picture and implement inorder, postorder and preorder traversals to it. p->data = data – Now, we have our node and we also have a space in memory allocated to it. return(p) – We are just returning the address of the node we created. That is, we cannot random access a node in a tree. Binary Search tree is a binary tree in which each internal node x stores an element such that the element stored in the left subtree of x are less than or equal to x and elements stored in the right subtree of x are greater than or equal to x. In this program, we need to create the binary tree by inserting nodes and displaying nodes in inorder fashion.