diff --git a/app.js b/app.js
index 6797a654..a0c9159e 100644
--- a/app.js
+++ b/app.js
@@ -1,132 +1,132 @@
-const express = require('express');
-const mongoose = require('mongoose');
-const bcrypt = require('bcrypt');
-const cors = require('cors');
-
-// Import required modules
-
-// Create an Express app
-const app = express();
-
-// Enable CORS
-app.use(express.json());
-app.use(cors());
-
-// Connect to MongoDB
-mongoose.connect('mongodb://localhost:27017/cafe', { useNewUrlParser: true, useUnifiedTopology: true })
-    .then(() => {
-        console.log('Connected to MongoDB');
-    })
-    .catch((error) => {
-        console.error('Error connecting to MongoDB:', error);
-    });
-
-// Define a user schema
-const userSchema = new mongoose.Schema({
-    username: { type: String, required: true },
-    password: { type: String, required: true }
-});
-
-// Define a user model
-const User = mongoose.model('User', userSchema);
-const productSchema = new mongoose.Schema({
-    name: { type: String, required: true },
-    price: { type: Number, required: true },
-    quantity: { type: Number, required: true }
-});
-const Product = mongoose.model('Product', productSchema);
-// Register a new user
-app.post('/register', async (req, res) => {
-    try {
-        const { username, password } = req.body;
-
-        // Check if the username already exists
-        const existingUser = await User.findOne({ username });
-        if (existingUser) {
-            return res.status(400).json({ message: 'Username already exists' });
-        }
-
-        // Hash the password
-        const hashedPassword = await bcrypt.hash(password, 10);
-
-        // Create a new user
-        const newUser = new User({ username, password: hashedPassword });
-        await newUser.save();
-
-        res.status(201).json({ message: 'User registered successfully' });
-    } catch (error) {
-        console.error('Error registering user:', error);
-        res.status(500).json({ message: 'Internal server error' });
-    }
-});
-
-// User login
-app.post('/login', async (req, res) => {
-    try {
-        const { username, password } = req.body;
-
-        // Find the user by username
-        const user = await User.findOne({ username });
-        if (!user) {
-            return res.status(404).json({ message: 'User not found' });
-        }
-
-        // Compare the password
-        const isPasswordValid = await bcrypt.compare(password, user.password);
-        if (!isPasswordValid) {
-            return res.status(401).json({ message: 'Invalid password' });
-        }
-
-        res.status(200).json({ message: 'Login successful' });
-    } catch (error) {
-        console.error('Error logging in:', error);
-        res.status(500).json({ message: 'Internal server error' });
-    }
-});
-
-app.get('/products',async (req,res)=>{
-    try{
-        const products = await Product.find();
-        res.status(200).json(products);
-    }catch(error){
-        console.error('Error getting products:',error);
-        res.status(500).json({message:'Internal server error'});
-    }
-})
-
-app.post('/products',async (req,res)=>{
-    try{
-        const {name,price,quantity} = req.body;
-        const newProduct = new Product({name,price,quantity});
-        await newProduct.save();
-        res.status(201).json({message:'Product added successfully'});
-    }catch(error){
-        console.error('Error adding product:',error);
-        res.status(500).json({message:'Internal server error'});
-    }
-})
-
-app.put('/products/:id',async (req,res)=>{
-    try{
-        const {name,price,quantity} = req.body;
-        await Product.findByIdAndUpdate(req.params.id,{name,price,quantity});
-        res.status(200).json({message:'Product updated successfully'});
-    }catch(error){
-        console.error('Error updating product:',error);
-        res.status(500).json({message:'Internal server error'});
-    }
-})
-
-app.delete('/products/:id',async (req,res)=>{
-    try{
-        await Product.findByIdAndDelete(req.params.id);
-        res.status(200).json({message:'Product deleted successfully'});
-    }catch(error){
-        console.error('Error deleting product:',error);
-        res.status(500).json({message:'Internal server error'});
-    }
-})
-// Start the server
-app.listen(3000, () => {
-    console.log('Server started on port 3000');
+const express = require('express');
+const mongoose = require('mongoose');
+const bcrypt = require('bcrypt');
+const cors = require('cors');
+
+// Import required modules
+
+// Create an Express app
+const app = express();
+
+// Enable CORS
+app.use(express.json());
+app.use(cors());
+
+// Connect to MongoDB
+mongoose.connect('mongodb://localhost:27017/cafe', { useNewUrlParser: true, useUnifiedTopology: true })
+    .then(() => {
+        console.log('Connected to MongoDB');
+    })
+    .catch((error) => {
+        console.error('Error connecting to MongoDB:', error);
+    });
+
+// Define a user schema
+const userSchema = new mongoose.Schema({
+    username: { type: String, required: true },
+    password: { type: String, required: true }
+});
+
+// Define a user model
+const User = mongoose.model('User', userSchema);
+const productSchema = new mongoose.Schema({
+    name: { type: String, required: true },
+    price: { type: Number, required: true },
+    quantity: { type: Number, required: true }
+});
+const Product = mongoose.model('Product', productSchema);
+// Register a new user
+app.post('/register', async (req, res) => {
+    try {
+        const { username, password } = req.body;
+
+        // Check if the username already exists
+        const existingUser = await User.findOne({ username });
+        if (existingUser) {
+            return res.status(400).json({ message: 'Username already exists' });
+        }
+
+        // Hash the password
+        const hashedPassword = await bcrypt.hash(password, 10);
+
+        // Create a new user
+        const newUser = new User({ username, password: hashedPassword });
+        await newUser.save();
+
+        res.status(201).json({ message: 'User registered successfully' });
+    } catch (error) {
+        console.error('Error registering user:', error);
+        res.status(500).json({ message: 'Internal server error' });
+    }
+});
+
+// User login
+app.post('/login', async (req, res) => {
+    try {
+        const { username, password } = req.body;
+
+        // Find the user by username
+        const user = await User.findOne({ username });
+        if (!user) {
+            return res.status(404).json({ message: 'User not found' });
+        }
+
+        // Compare the password
+        const isPasswordValid = await bcrypt.compare(password, user.password);
+        if (!isPasswordValid) {
+            return res.status(401).json({ message: 'Invalid password' });
+        }
+
+        res.status(200).json({ message: 'Login successful' });
+    } catch (error) {
+        console.error('Error logging in:', error);
+        res.status(500).json({ message: 'Internal server error' });
+    }
+});
+
+app.get('/products',async (req,res)=>{
+    try{
+        const products = await Product.find();
+        res.status(200).json(products);
+    }catch(error){
+        console.error('Error getting products:',error);
+        res.status(500).json({message:'Internal server error'});
+    }
+})
+
+app.post('/products',async (req,res)=>{
+    try{
+        const {name,price,quantity} = req.body;
+        const newProduct = new Product({name,price,quantity});
+        await newProduct.save();
+        res.status(201).json({message:'Product added successfully'});
+    }catch(error){
+        console.error('Error adding product:',error);
+        res.status(500).json({message:'Internal server error'});
+    }
+})
+
+app.put('/products/:id',async (req,res)=>{
+    try{
+        const {name,price,quantity} = req.body;
+        await Product.findByIdAndUpdate(req.params.id,{name,price,quantity});
+        res.status(200).json({message:'Product updated successfully'});
+    }catch(error){
+        console.error('Error updating product:',error);
+        res.status(500).json({message:'Internal server error'});
+    }
+})
+
+app.delete('/products/:id',async (req,res)=>{
+    try{
+        await Product.findByIdAndDelete(req.params.id);
+        res.status(200).json({message:'Product deleted successfully'});
+    }catch(error){
+        console.error('Error deleting product:',error);
+        res.status(500).json({message:'Internal server error'});
+    }
+})
+// Start the server
+app.listen(3000, () => {
+    console.log('Server started on port 3000');
 });
\ No newline at end of file
diff --git "a/\342\200\216Data-Structures-and-Algorithms-for-Interviews/Main.java" "b/\342\200\216Data-Structures-and-Algorithms-for-Interviews/Main.java"
new file mode 100644
index 00000000..58598909
--- /dev/null
+++ "b/\342\200\216Data-Structures-and-Algorithms-for-Interviews/Main.java"
@@ -0,0 +1,80 @@
+// Following program is a Java implementation
+// of Rabin Karp Algorithm given in the CLRS book
+
+public class Main {
+	// d is the number of characters in the input alphabet
+	public final static int d = 256;
+
+	/* pat -> pattern
+		txt -> text
+		q -> A prime number
+	*/
+	static void search(String pat, String txt, int q)
+	{
+		int M = pat.length();
+		int N = txt.length();
+		int i, j;
+		int p = 0; // hash value for pattern
+		int t = 0; // hash value for txt
+		int h = 1;
+
+		// The value of h would be "pow(d, M-1)%q"
+		for (i = 0; i < M - 1; i++)
+			h = (h * d) % q;
+
+		// Calculate the hash value of pattern and first
+		// window of text
+		for (i = 0; i < M; i++) {
+			p = (d * p + pat.charAt(i)) % q;
+			t = (d * t + txt.charAt(i)) % q;
+		}
+
+		// Slide the pattern over text one by one
+		for (i = 0; i <= N - M; i++) {
+
+			// Check the hash values of current window of
+			// text and pattern. If the hash values match
+			// then only check for characters one by one
+			if (p == t) {
+				/* Check for characters one by one */
+				for (j = 0; j < M; j++) {
+					if (txt.charAt(i + j) != pat.charAt(j))
+						break;
+				}
+
+				// if p == t and pat[0...M-1] = txt[i, i+1,
+				// ...i+M-1]
+				if (j == M)
+					System.out.println(
+						"Pattern found at index " + i);
+			}
+
+			// Calculate hash value for next window of text:
+			// Remove leading digit, add trailing digit
+			if (i < N - M) {
+				t = (d * (t - txt.charAt(i) * h)
+					+ txt.charAt(i + M))
+					% q;
+
+				// We might get negative value of t,
+				// converting it to positive
+				if (t < 0)
+					t = (t + q);
+			}
+		}
+	}
+
+	/* Driver Code */
+	public static void main(String[] args)
+	{
+		String txt = "GEEKS FOR GEEKS";
+		String pat = "GEEK";
+
+		// A prime number
+		int q = 101;
+
+		// Function Call
+		search(pat, txt, q);
+	}
+}
+