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Binary search tree algorithm
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‎binary-search-tree/index.html‎

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<!DOCTYPE html>
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<html>
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<head>
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<title>Binary Search Tree DataStructure</title>
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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</head>
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<body>
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<h1>Binary Search Tree DataStructure</h1>
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<h4>open dev tools and see the console</h4>
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<script src="js/index.js"></script>
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</body>
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</html>

‎binary-search-tree/js/index.js‎

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(function () {
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/**
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* function to create tree node
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* @param {*} data
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*/
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const Node = function (data = null) {
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this.data = data;
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this.left = null;
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this.right = null;
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}
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const BinarySearchTree = function () {
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let root = null;
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let traversalResult = [];
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// function to insert node in the tree
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const insert = data => {
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const node = new Node(data);
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root ? insertNode(root, node) : root = node;
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}
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// helper function to locate the node position to insert in the tree
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const insertNode = (parentNode, node) => {
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if (node.data < parentNode.data) {
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if (parentNode.left === null) {
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parentNode.left = node;
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} else {
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insertNode(parentNode.left, node)
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}
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} else {
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if (parentNode.right === null) {
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parentNode.right = node;
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} else {
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insertNode(parentNode.right, node)
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}
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}
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}
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// function to remove the node with data in argument and updates the root node
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const remove = data => {
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root = removeNode(root, data);
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}
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// helper function to locate the node matching the data and remove and update the branch
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const removeNode = (parentNode, data) => {
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if (parentNode === null) {
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return parentNode;
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} else if (data < parentNode.data) {
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parentNode.left = removeNode(parentNode.left, data);
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return parentNode;
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} else if (data > parentNode.data) {
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parentNode.right = removeNode(parentNode.right, data);
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return parentNode;
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} else {
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const { left, right } = parentNode;
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if (left === null && right === null) {
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parentNode = null;
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return parentNode;
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}
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if (left === null) {
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parentNode = parentNode.right;
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return parentNode;
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} else if (right === null) {
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parentNode = parentNode.left;
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return parentNode;
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}
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// find minRightNode value and replace the parentNode value with that
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const minRightNode = findMinNode(parentNode.right);
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parentNode.data = minRightNode.data;
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// then remove the minRightNode from the right sub tree
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parentNode.right = removeNode(parentNode.right, minRightNode.data);
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return parentNode;
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}
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}
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// finds the minimum node in tree
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// searching starts from given node
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const findMinNode = node => {
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// if left of a node is null
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// then it must be minimum node
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if (node.left === null)
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return node;
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else
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return findMinNode(node.left);
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}
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// function to search for a node with given data
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// this method uses depth first algorithm
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const search = (data, parentNode = root) => {
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// if trees is empty return null
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if (parentNode === null) {
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return null;
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}
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// if data is less than node's data
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// move left
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else if (data < parentNode.data) {
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return search(parentNode.left, data);
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}
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// if data is less than node's data
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// move left
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else if (data > parentNode.data) {
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return search(parentNode.right, data);
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}
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// if data is equal to the node data
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// return parentNode
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else {
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return parentNode;
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}
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}
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// returns root of the tree
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const getRootNode = () => root;
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const traversalMode = {
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'inorder': Symbol('inorder'),
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'preorder': Symbol('preorder'),
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'postorder': Symbol('postorder')
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};
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const inOrderTraversal = (node) => {
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if (node !== null) {
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inOrderTraversal(node.left);
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traversalResult.push(node.data);
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inOrderTraversal(node.right);
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}
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}
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const preOrderTraversal = (node) => {
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if (node !== null) {
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traversalResult.push(node.data);
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preOrderTraversal(node.left);
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preOrderTraversal(node.right);
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}
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}
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const postOrderTraversal = (node) => {
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if (node !== null) {
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postOrderTraversal(node.left);
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postOrderTraversal(node.right);
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traversalResult.push(node.data);
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}
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}
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const traversal = (mode = traversalMode.inorder, node = root) => {
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traversalResult = [];
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switch (mode) {
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case traversalMode.inorder:
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inOrderTraversal(node);
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break;
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case traversalMode.preorder:
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preOrderTraversal(node);
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break;
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case traversalMode.postorder:
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postOrderTraversal(node);
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break;
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}
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return traversalResult.join(' -> ');
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}
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return Object.freeze({
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insert,
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remove,
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traversal,
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traversalMode,
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getRootNode,
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search
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});
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}
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const bst = new BinarySearchTree();
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console.log('Inserting nodes to the BinarySearchTree');
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bst.insert(15);
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bst.insert(25);
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bst.insert(10);
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bst.insert(7);
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bst.insert(22);
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bst.insert(17);
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bst.insert(13);
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bst.insert(5);
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bst.insert(9);
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bst.insert(27);
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console.log('tree result after insertion');
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console.log(JSON.stringify(bst.getRootNode(), 0, 4));
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console.log('inorder traversal from root node');
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console.log(bst.traversal(bst.traversalMode.inorder));
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console.log('preorder traversal from root node');
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console.log(bst.traversal(bst.traversalMode.preorder));
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console.log('postorder traversal from root node');
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console.log(bst.traversal(bst.traversalMode.postorder));
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console.log('Removing node with no children - 5');
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bst.remove(5);
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console.log('inorder traversal from root node after removing 5');
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console.log(bst.traversal(bst.traversalMode.inorder));
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console.log('Removing node with one children - 7');
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bst.remove(7);
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console.log('inorder traversal from root node after removing 7');
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console.log(bst.traversal(bst.traversalMode.inorder));
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console.log('Removing node with two children - 15');
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bst.remove(15);
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console.log('inorder traversal from root node after removing 15');
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console.log(bst.traversal(bst.traversalMode.inorder));
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console.log('preorder traversal from root node after removing 15');
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console.log(bst.traversal(bst.traversalMode.preorder));
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console.log('postorder traversal from root node after removing 15');
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console.log(bst.traversal(bst.traversalMode.postorder));
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console.log('tree result after removing 5, 7 and 15');
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console.log(JSON.stringify(bst.getRootNode(), 0, 4));
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})();

‎binary-search-tree/readme.md‎

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# Binary Search Tree DataStructure #

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