--update : add BTree

Author: TheSTL

README.md

@@ -49,6 +49,7 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
     - [Find Height of BST](src/_DataStructures_/Trees/BinarySearchTree/height-of-bst)
     - [Find k Nodes from Root of BST](src/_DataStructures_/Trees/BinarySearchTree/find-k-nodes-from-root)
   - [Suffix Tree](src/_DataStructures_/SuffixTree)
+  - [BTree](src/_DataStructures_/BTree)
 
 ### Logical Problems
 

src/_DataStructures_/Trees/BTree/Node.js

@@ -0,0 +1,9 @@
+module.exports = class Node {
+  constructor(t, isLeaf) {
+    this.t = t;
+    this.isLeaf = isLeaf;
+    this.keys = [];
+    this.child = [];
+    this.totalKey = 0;
+  }
+};

src/_DataStructures_/Trees/BTree/index.js

@@ -0,0 +1,114 @@
+/* eslint-disable class-methods-use-this */
+/* eslint-disable no-param-reassign */
+const Node = require('./Node');
+
+class BTree {
+  constructor(t) {
+    this.t = t;
+    this.root = null;
+  }
+
+  splitChild(index, parent, y) {
+    const z = new Node(this.t, y.isLeaf);
+    z.totalKey = this.t - 1;
+
+    for (let i = 0; i < this.t - 1; i += 1) {
+      z.keys.push(y.keys[this.t + i]);
+    }
+
+    if (y.isLeaf === false) {
+      for (let i = 0; i < this.t; i += 1) {
+        z.child.push(y.child[this.t + 1]);
+      }
+      y.child = y.child.slice(0, this.t);
+    }
+    y.totalKey = this.t - 1;
+
+    for (let i = parent.totalKey; i >= index + 1; i -= 1) {
+      parent.child[i + 1] = parent.child[i];
+    }
+    parent.child[index + 1] = z;
+
+    for (let i = parent.totalKey - 1; i >= index; i -= 1) {
+      parent.keys[i + 1] = parent.keys[i];
+    }
+
+    parent.keys[index] = y.keys[this.t - 1];
+    y.keys = y.keys.slice(0, this.t - 1);
+    parent.totalKey += 1;
+  }
+
+  insertNonFull(node, key) {
+    let i = node.totalKey - 1;
+
+    if (node.isLeaf === true) {
+      while (i >= 0 && node.keys[i] > key) {
+        node.keys[i + 1] = node.keys[i];
+        i -= 1;
+      }
+      node.keys[i + 1] = key;
+      node.totalKey += 1;
+    } else {
+      while (i >= 0 && node.keys[i] > key) i -= 1;
+
+      if (node.child[i + 1].totalKey === 2 * this.t - 1) {
+        this.splitChild(i + 1, node, node.child[i + 1]);
+
+        if (node.keys[i + 1] < key) i += 1;
+      }
+      this.insertNonFull(node.child[i + 1], key);
+    }
+  }
+
+  insert(key) {
+    if (this.root === null) {
+      this.root = new Node(this.t, true);
+      this.root.keys.push(key);
+      this.root.totalKey = 1;
+    } else if (this.root.totalKey === 2 * this.t - 1) {
+      const newRoot = new Node(this.t, false);
+      newRoot.child[0] = this.root;
+      this.splitChild(0, newRoot, this.root);
+      let i = 0;
+      if (newRoot.keys[i] < key) i += 1;
+      this.insertNonFull(newRoot.child[i], key);
+      this.root = newRoot;
+    } else {
+      this.insertNonFull(this.root, key);
+    }
+  }
+}
+
+// const tree = new BTree(3);
+// tree.insert(10);
+// tree.insert(20);
+// tree.insert(30);
+// tree.insert(40);
+// tree.insert(50);
+// tree.insert(60);
+// tree.insert(70);
+// tree.insert(80);
+// tree.insert(90);
+// tree.insert(100);
+// tree.insert(110);
+// tree.insert(120);
+// tree.insert(130);
+// tree.insert(140);
+// tree.insert(150);
+// tree.insert(160);
+
+
+// console.log('----root---');
+// console.log(tree.root);
+
+// console.log('----child0---');
+// console.log(tree.root.child[0]);
+
+// console.log('----child1---');
+// console.log(tree.root.child[1]);
+
+// console.log('----child2---');
+// console.log(tree.root.child[2]);
+
+
+module.export = BTree;