Numerical Problems

Find Roots of a quadratic equation

import java.util.Scanner;
public class QuadraticEquation {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);

System.out.print("Enter the coefficient a: ");
double a = scanner.nextDouble();

System.out.print("Enter the coefficient b: ");
double b = scanner.nextDouble();


System.out.print("Enter the coefficient c: ");
double c = scanner.nextDouble();


double discriminant = b * b - 4 * a * c;
double root1, root2;


if (discriminant > 0) {
    root1 = (-b + Math.sqrt(discriminant)) / (2 * a);
    root2 = (-b - Math.sqrt(discriminant)) / (2 * a);
    System.out.println("The roots are real and different.");
    System.out.println("Root 1: " + root1);
    System.out.println("Root 2: " + root2);

        } else if (discriminant == 0) {

root1 = root2 = -b / (2 * a);
System.out.println("The roots are real and the same.");
System.out.println("Root 1 = Root 2: " + root1);
}
else {
double realPart = -b / (2 * a);
double imaginaryPart = Math.sqrt(-discriminant) / (2 * a);
System.out.println("The roots are complex and different.");

System.out.println("Root 1: " + realPart + " + " + imaginaryPart + "i");
System.out.println("Root 2: " + realPart + " - " + imaginaryPart + "i");
}

scanner.close();
}
}

**********************************************************
Learn switch case

import java.util.Scanner;

public class CaseStatementExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Choose an option:");
        System.out.println("1. Say Hello");
        System.out.println("2. Display Date");
        System.out.println("3. Exit");

        int choice = scanner.nextInt();

        switch (choice) {
            case 1:
                System.out.println("Hello!");
                break;
            case 2:
                java.util.Date date = new java.util.Date();
                System.out.println("Current date and time: " + date.toString());
                break;
            case 3:
                System.out.println("Exiting the program...");
                break;
            default:
                System.out.println("Invalid choice! Please choose a valid option.");
                break;
        }

        scanner.close();
    }
}

*****************************************************

Check for Prime

import java.util.Scanner;

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

public static boolean isPrime(int num) {
if (num <= 1) {
return false;
}

for (int i = 2; i <= Math.sqrt(num); i++) {
if (num % i == 0) {
    return false;
}
}
return true;
}
}
***********************************************
Fibonacci Series Using Recursion
import java.util.Scanner;

public class FibonacciSeries {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the number of terms: ");
        int terms = scanner.nextInt();

        System.out.println("Fibonacci Series up to " + terms + " terms:");

        for (int i = 0; i < terms; i++) {
            System.out.print(fibonacci(i) + " ");
        }

        scanner.close();
    }

    public static int fibonacci(int n) {
        if (n <= 1) {
            return n;
        }
        return fibonacci(n - 1) + fibonacci(n - 2);
    }
}
****************************************************
Prime number <1000 using nested loops
public class PrimeNumbers {
    public static void main(String[] args) {
        System.out.println("Prime numbers less than 1000:");

        for (int num = 2; num < 1000; num++) {
            boolean isPrime = true;

            for (int i = 2; i <= Math.sqrt(num); i++) {
                if (num % i == 0) {
                    isPrime = false;
                    break;
                }
            }

            if (isPrime) {
                System.out.print(num + " ");
            }
        }
    }
}

*************************************************************
gcd of two numbers using Euclid algorithm

import java.util.Scanner;

public class GCD {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the first number: ");
        int num1 = scanner.nextInt();

        System.out.print("Enter the second number: ");
        int num2 = scanner.nextInt();

        int gcd = findGCD(num1, num2);

        System.out.println("The GCD of " + num1 + " and " + num2 + " is: " + gcd);

        scanner.close();
    }

    public static int findGCD(int a, int b) {
        while (b != 0) {
            int temp = b;
            b = a % b;
            a = temp;
        }
        return a;
    }
}

***************************************************************************
Sum of digits, reverse and palindrome check

import java.util.Scanner;

public class DigitBasedOperations {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter a positive integer: ");
        int number = scanner.nextInt();

        int sumOfDigits = calculateSumOfDigits(number);
        int reversedNumber = reverseNumber(number);
        boolean isPalindrome = checkPalindrome(number);

        System.out.println("Sum of digits: " + sumOfDigits);
        System.out.println("Reversed number: " + reversedNumber);
        System.out.println("Is palindrome: " + isPalindrome);

        scanner.close();
    }

    public static int calculateSumOfDigits(int num) {
        int sum = 0;
        while (num != 0) {
            sum += num % 10;
            num /= 10;
        }
        return sum;
    }

    public static int reverseNumber(int num) {
        int reversed = 0;
        while (num != 0) {
            int digit = num % 10;
            reversed = reversed * 10 + digit;
            num /= 10;
        }
        return reversed;
    }

    public static boolean checkPalindrome(int num) {
        return num == reverseNumber(num);
    }
}

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