Find GCD of two numbers in Java?

Code :

/**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 6/12/13
 * Time: 4:46 PM
 * To change this template use File | Settings | File Templates.
 */
public class GCDFinder {

    public static int gcd(int a,int b){
        int temp = a % b;
        if(temp == 0)
            return b;
        else
            return gcd(b,temp);
        }

    public static void main(String args[]){
        System.out.println("GCD of 12 and 10 is : " + gcd(12,10));
    }
}

Output :

GCD of 12 and 10 is : 2

Note : You can calculate LCM as Number1*Number2/GCD

Find nth Fibonacci number in Java?

Fibonacci series is as follows

1 1 2 3 5 8 13 21 34...

You can read more about this sequence in Wiki.

Again for this we can have iterative approach as well as recursive. Recursive code is provided below

Recursive Code :

 /**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 6/12/13
 * Time: 3:25 PM
 * To change this template use File | Settings | File Templates.
 */
public class FibonacciFinder {

    public static int fibonacci(int number){

        if(number <= 2){
            return 1;
        }
        else{
            return  fibonacci(number - 1) + fibonacci(number - 2);
        }
    }

    public static void main(String args[]){

        System.out.println("8th fibonacci number is : " + fibonacci(8));


    }

}

Output :

8th fibonacci number is : 21

Iterative Code :

/**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 6/12/13
 * Time: 3:25 PM
 * To change this template use File | Settings | File Templates.
 */
public class FibonacciFinder {
    int prev = 1;
    int curr = 1;
    public int fibonacci(int number){

        if(number < 2){
            return curr;
        }
        else {
            int temp;
            for(int i = 0;i<number-2;i++){
                temp = curr;
                curr = curr + prev;
                prev = temp;
            }
            return curr;
        }
    }

    public static void main(String args[]){

        System.out.println("8th fibonacci number is : " + (new FibonacciFinder()).fibonacci(8));
    }

}

Output:

8th fibonacci number is : 21

 

Find Power of a number in Java?

There are two ways to find power of a number. One is iterative which is very simple(Just multiply the number power number of times) and other is recursive. Following is the code to get power of a number in recursive way.

Code : 

/**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 6/12/13
 * Time: 3:08 PM
 * To change this template use File | Settings | File Templates.
 */
public class PowerCalculator {

    public static int pow(int base, int power){

        if(power == 1){
            return base;
        }
        if(power % 2 == 0){
            return pow(base, power/2) * pow(base, power/2);
        }
        else {
            return pow(base, power/2) * pow(base, power/2) + base;
        }
    }

    public static void main(String args []){

        System.out.println("4 raise to 2 : " + PowerCalculator.pow(4,2));

    }

}

Output :

4 raise to 2 : 16

Find factorial of a number in Java?

There are two ways to find factorial of a number. One is iterative which is very simple and other is recursive. Following is the code to get factorial by recursive method.

Code :

/**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 6/12/13
 * Time: 2:52 PM
 * To change this template use File | Settings | File Templates.
 */
public class FactorialFinder {

    public static int factorial(int no){

        if(no < 0){
            throw new RuntimeException("Number cannot be Negative");
        }
        else if(no == 1){
            return no;
        }
        else{
            return no * factorial(no - 1);
        }

    }

    public static void main(String args[]){
        int number = 4;
        System.out.printf("Factorial of 4 is : " + FactorialFinder.factorial(4));
    }


}

Output

Factorial of 4 is : 24