Create Trees.md

Author: ps0305

Basic Data Structures/Implementation of Binary Search Tree in Javascript/Trees.md

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+A tree is a data structure where a node can have zero or more children. Each node contains a value, and similar to graphs each node can have a connection between other
+nodes called an edge. A tree is a type of graph but not all graphs are trees.
+
+The top-most node is called the root. The DOM, or document object model, is a tree data structure. 
+
+A node without children is called a leaf node.
+
+The height of the tree is the distance between the farthest leaf node and the root node.
+
+![image](https://user-images.githubusercontent.com/34129569/158032297-e2075025-4c71-4a7e-ad9c-d330c092ef7b.png)
+
+## Binary Trees
+
+Binary trees are a special type of tree in which each node can only have a maximum of two children: a left child and a right child.
+
+![image](https://user-images.githubusercontent.com/34129569/158032318-88962e4b-a6c5-44fa-a6b4-5c28109e639d.png)
+
+##  Binary Search Tree
+
+```js
+// Node class
+class Node
+{
+	constructor(data)
+	{
+		this.data = data;
+		this.left = null;
+		this.right = null;
+	}
+}
+```
+
+As in the above code snippet we define a node class having three property data, left and right, Left and right are pointers to the left and right node in a Binary Search Tree. Data is initialized with data which is passed when object for this node is created and left and right is set to null.
+
+Now let’s see an example of a Binary Search Tree class. 
+
+```js
+// Binary Search tree class
+class BinarySearchTree
+{
+	constructor()
+	{
+		// root of a binary search tree
+		this.root = null;
+	}
+
+	// function to be implemented
+	// insert(data)
+	// remove(data)
+				
+
+	// Helper function
+	// findMinNode()
+	// getRootNode()
+	// inorder(node)
+	// preorder(node)			
+	// postorder(node)
+	// search(node, data)
+}
+```
+
+The above example shows a framework of a Binary Search tree class, which contains a private variable root which holds the root of a tree, it is initialized to null. 
+
+Now lets implement each of this function: 
+
+**1. insert(data)** – It inserts a new node in a tree with a value data
+
+```js
+// helper method which creates a new node to
+// be inserted and calls insertNode
+insert(data)
+{
+	// Creating a node and initialising
+	// with data
+	var newNode = new Node(data);
+					
+	// root is null then node will
+	// be added to the tree and made root.
+	if(this.root === null)
+		this.root = newNode;
+	else
+
+		// find the correct position in the
+		// tree and add the node
+		this.insertNode(this.root, newNode);
+}
+
+// Method to insert a node in a tree
+// it moves over the tree to find the location
+// to insert a node with a given data
+insertNode(node, newNode)
+{
+	// if the data is less than the node
+	// data move left of the tree
+	if(newNode.data < node.data)
+	{
+		// if left is null insert node here
+		if(node.left === null)
+			node.left = newNode;
+		else
+
+			// if left is not null recur until
+			// null is found
+			this.insertNode(node.left, newNode);
+	}
+
+	// if the data is more than the node
+	// data move right of the tree
+	else
+	{
+		// if right is null insert node here
+		if(node.right === null)
+			node.right = newNode;
+		else
+
+			// if right is not null recur until
+			// null is found
+			this.insertNode(node.right,newNode);
+	}
+}
+```