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Root node is the topmost node of the tree. In this representation, array structure is used to implement the tree. Size of array is equal to the total nodes in the tree, index of root node is 0. Visual Representation:. As you can see, the topmost node is the parent node of nodes "B" and "C".

Each node contains a pointer to the left subtree and pointer to the right subtree. Node A has a pointer to the left child that is B and a pointer pointing to the right child of A that is B. Middle box represents the data in the node.

The nodes which doesn't have a child are called ass leaf nodes. These nodes do not have pointer to their subtrees. Therefore left and right pointers are set to NULL.

The left sub tree of a node only contain nodes less than the parent node's key. The right sub tree of a node only contains nodes greter than the parent node's key. We will now a implement Binary tree using Linked list representation.

We will use a class to declare a single node and use it to declare linked list of nodes. When we want to declare a group of data whether of similar or different data types.

We classes in cpp. Declared using 'class' keyword. Our class is "BSTNode" containing a pointer to left and pointer to right. Stores the address of left child. Its important to understand the concepts of stack and memory, heaps in dynamic allocation.

For linked list we keep the information of address of the head node. We can access al other links using head node using links. In this case we know the address of the root node, which is must, without this we won't be able to access the tree using links. Our tree does not have any data yet, so let us assign our root node as NULL. As seen, we are assigning the left and right cells of nodes as addresses to their child and middle cell is for data.

Identity of tree is address of the root node, and we have declared a pointer to node in which we are storing address of root node. For empty tree root pointer should be set as NULL. Consider this rootPtr as a different box pointing towards different nodes in our tree, and for pointing to different nodes we have to pass the address of the nodes. In the beginning it is not pointing towards any node and therfore NULL value. Asked 5 years, 6 months ago. Active 5 years, 6 months ago.

Viewed 7k times. Improve this question. Karthikeyan Sivakumar Karthikeyan Sivakumar 27 1 1 silver badge 1 1 bronze badge. Did you download the library? Add a comment. Active Oldest Votes. Improve this answer.

Mitsos Mitsos 3 3 silver badges 14 14 bronze badges. AbhinandanDharmadhikari wants to add such a comment for this answer I think: "what if the person is using mac os? Alex Zywicki Alex Zywicki 2, 1 1 gold badge 16 16 silver badges 31 31 bronze badges. A binary tree comprises of parent nodes, or leaves, each of which stores data and also links to up to two other child nodes leaves which are visualized spatially as below the first node with one placed to the left and with one placed to the right.

So, we created a class Node comprising of :Data to be stored, Left subtree pointer, Right subtree pointer, Parameterised constructor node along with two functions:- 1. Build tree 2. Print taking the root node as an argument. The buildtree inputs the value of data in variable d and root node is locally created with the data as d. The condition checks if the tree is empty if empty return NULL or not.

The recursive call of function buildtree is made on both left and right subtree of the binary tree and then root is returned. The print function accepting root node is used to print the entire binary tree.

If the tree is empty, no tree is printed. Else, the data of the root node is printed first followed by the recursive call of print function on both left and right subtree.

A binary tree is build up and printed in main function by calling both functions.