Updated BinarySearchTree.java with comments

Author: mahesh-11102

Data Structure/Trees/Binary Trees/BinarySearchTree.java

@@ -4,10 +4,11 @@
 import java.util.*;
 import java.io.*;
 
+// initializing node class
 class Node {
 	int data;
 	Node left, right;
-	Node(int x)
+	Node(int x) // Node contructor 
 	{
 		data = x;
 		left = right = null;
@@ -17,27 +18,31 @@ class Node {
 public class BinaryTree {
 
 	static int count = 0;
-	public static Node insert(Node root, int x)
+	// insertion of element using recursion
+	public static Node insert(Node root, int data)
 	{
 		if (root == null)
-			return new Node(x);
-		if (x < root.data)
-			root.left = insert(root.left, x);
-		else if (x > root.data)
-			root.right = insert(root.right, x);
+			return new Node(data);
+		if (data < root.data) // if the data is less than node data go left
+			root.left = insert(root.left, data);
+		
+		else if (data > root.data)  // if data is greater than node data go right
+			root.right = insert(root.right, data);
+		
 		return root;
 	}
 
 	public static Node kthSmallest(Node root, int k)
 	{
 		if (root == null)
 			return null;
-		Node left = kthSmallest(root.left, k);
+		Node left = kthSmallest(root.left, k); // at this line we go to leftmost node, so that  we can start counting nth smallest from thatnode (leftmost)
 
 		if (left != null)
-			return left;
-			count++;
-		if (count == k)
+			return left; 
+		count++;
+		
+		if (count == k) // if we find the element at k return k;
 			return root;
 
 		return kthSmallest(root.right, k);
@@ -46,8 +51,8 @@ public static Node kthSmallest(Node root, int k)
 	public static void printKthSmallest(Node root, int k)
 	{
 		count = 0;
+		Node res = kthSmallest(root, k); // get the smallest element 
 
-		Node res = kthSmallest(root, k);
 		if (res == null)
 			System.out.println("can't print as k is greater than nodes");
 		else
@@ -56,15 +61,16 @@ public static void printKthSmallest(Node root, int k)
 
 	public static void main (String[] args) {
 		Scanner take = new Scanner(System.in);
-		Node root = null;
-        System.out.print("enter number of elements in the list: ");
-		int size = take.nextInt();
+		Node root = null; // initialising root node
+		
+        	System.out.print("enter number of elements in the list: ");
+			int size = take.nextInt();
 
-        while(size-- !=0)
-			root = insert(root, take.nextInt());
+	        while(size-- !=0)
+			root = insert(root, take.nextInt());  // calling insert method to insert the element in the tree
 		System.out.print("enter k: ");
 		int k = take.nextInt();
-		printKthSmallest(root, k);
+		printKthSmallest(root, k); //calling this function to find the kth smallest element
 
 
 	}