Question

FOR JAVA We have the notion in the mathematics of factorial. This is summarized by the following formula

x! == x * (x-1) * (x-2) * … * 2 * 1

4! = 4 * 3 * 2 * 1

I want you to solve this in two ways. Solve it first using a for-loop and then again using recursion in java.

Answer 1

import java.util.Scanner;
public class FactorialLoop {
    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);
        int n;
        System.out.print("Enter an integer: ");
        n = scanner.nextInt();
        int res = factorial(n);
        System.out.println(res);
    }

    private static int factorial(int n) {
        int res = 1;
        for(int i = 2;i<=n;i++){
            res *= i;
        }
        return res;
    }
}

//////////////////////////////////////////////////////////

import java.util.Scanner;

public class FactorialRecursion {
    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);
        int n;
        System.out.print("Enter an integer: ");
        n = scanner.nextInt();
        int res = factorial(n);
        System.out.println(res);
    }

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