JAVA: (Feel free to test me on concepts shown below even during my sleep)

1. Reverse a String
This program takes a string input from the user and reverses it:

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a number: ");
        int num = scanner.nextInt();
        System.out.println("Factorial of " + num + " = " + factorial(num));
    }

    static int factorial(int n) {
        if (n == 0 || n == 1) return 1;
        else return n * factorial(n - 1);
    }
}


2. Factorial of a Number
This program calculates the factorial of a given number using recursion.

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a number: ");
        int num = scanner.nextInt();
        System.out.println("Factorial of " + num + " = " + factorial(num));
    }

    static int factorial(int n) {
        if (n == 0 || n == 1) return 1;
        else return n * factorial(n - 1);
    }
}




3. Fibonacci Sequence
This program generates the Fibonacci sequence up to a specified number of terms.

import java.util.Scanner;

public class Fibonacci {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter the number of terms: ");
        int terms = scanner.nextInt();
        int a = 0, b = 1;
        System.out.print("Fibonacci Series: ");
        for (int i = 0; i < terms; i++) {
            System.out.print(a + " ");
            int nextTerm = a + b;
            a = b;
            b = nextTerm;
        }
    }
}



4. Palindrome Check
This program checks whether a given string is a palindrome.

import java.util.Scanner;

public class PalindromeCheck {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a string: ");
        String str = scanner.nextLine();
        String reversed = new StringBuilder(str).reverse().toString();
        if (str.equals(reversed)) {
            System.out.println(str + " is a palindrome");
        } else {
            System.out.println(str + " is not a palindrome");
        }
    }
}




5. Prime Number Check
​This program checks whether a given number is prime.

import java.util.Scanner;

public class PrimeCheck {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a number: ");
        int num = scanner.nextInt();
        if (isPrime(num)) {
            System.out.println(num + " is a prime number");
        } else {
            System.out.println(num + " is not a prime number");
        }
    }

    static boolean isPrime(int n) {
        if (n <= 1) return false;
        for (int i = 2; i <= Math.sqrt(n); i++) {
            if (n % i == 0) return false;
        }
        return true;
    }
}

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