chore: added binary tree

Author: rupeshtiwari

.vscode/spellright.dict

@@ -0,0 +1 @@
+logn

README.md

@@ -53,7 +53,7 @@ Given a sorted array of integers, return the index of the given key. Return -1 i
 Run below script
 
 ```
-node .\src\arrays\binary-search.mjs
+node .\src\arrays\binary-search.js
 ```
 
 ### Find Maximum in Sliding Window
@@ -67,7 +67,42 @@ Given a large array of integers and a window of size w, find the current maximum
 Divide two integers without using '/' (division) or '\*' (multiplication) operators.
 
 ```shell
-node .\src\math-and-stats\integer-division.mjs
+node .\src\math-and-stats\integer-division.js
 ```
 
 ![](https://imgur.com/Cf7cz4W.png)
+
+## Mock Interview
+
+### Get the Average value at each level of the tree
+
+![](https://imgur.com/N6agnSk.png)
+
+Traverse by depth and collect all the numbers.
+And calculate average also.
+
+Runtime Complexity
+O(logn)
+Space Complexity
+O(logn)
+
+## Binary Tree
+
+A binary tree is a type of tree in which each node has at most two children (0, 1 or 2) which are referred as left child and right child.
+
+## Binary Search Tree (BST)
+
+In Binary Search Tree nodes are:
+
+- The key in the left subtree is less than the key in its parent node.
+- The key in the right subtree is greater or equal the key in its parent node.
+
+![](https://i.imgur.com/Dk04fw4.png)
+
+### Level Order Traversal
+
+**Level Order traversal** is also known as **Breadth-First Traversal** since it traverses all the nodes at each level before going to the next level (depth). The last level of the tree is always equal to the height of the tree. The last level of the tree should contain at least one Node.
+
+
+#### ADT
+abstract data type (ADT) 

src/arrays/binary-search.mjs

@@ -29,7 +29,7 @@
  Runtime Complexity: O(log n)
  Memory Complexity: O(log n)
 */
-export function recursiveBinarySearch(arr, key, low, high) {
+function recursiveBinarySearch(arr, key, low, high) {
   if (low > high) {
     return -1;
   }
@@ -80,7 +80,7 @@ for (var i = 0; i < inputs.length; i++) {
  Runtime Complexity: O(log n)
  Memory Complexity: O(1)
 */
-export function iterativeBinarySearch(arr, key) {
+ function iterativeBinarySearch(arr, key) {
   let low = 0;
   let high = arr.length - 1;
   let mid;

src/arrays/find-max-sliding-window.js renamed to src/arrays/find-max-sliding-window.mjs

@@ -0,0 +1,12 @@
+class Node {
+  value;
+  left;
+  right;
+  constructor(value, left, right) {
+    this.value = value;
+    this.left = left;
+    this.right = right;
+  }
+}
+
+

src/mock-interview/find-average-in-binary-tree.mjs

@@ -0,0 +1,11 @@
+class BinaryTreeNode {
+  constructor(value) {
+    this.value = value;
+    this.left = null;
+    this.right = null;
+
+    this.next = null;
+    this.parent = null;
+    this.count = null;
+  }
+}