Loops.java

import java.io.*;
import java.util.*;

public class Loops {

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

    public int fact2(int n) {
	int product = 1;
	while (n > 1) {
	    product = product * n;
	    n = n-1;
	}
	return product;
    }

    public int gcd(int a, int b) {
	int divisor;
	// if either number is 0, return the other number
	if (a==0) {
	    return b;
	}
	else if (b==0) {
	    return a;
	}
	// if both numbers are equal, return the number
	else if (a == b) {
	    return a;
	}
	// initialize the divisor
	else if (a > b) {
	    divisor = b;
	}
	else {
	    divisor = a;
	}

	while (divisor > 1) {
	    if (a%divisor == 0 && b%divisor == 0) {
		return divisor;
	    }
	    else {
		divisor = divisor - 1;
	    }
	}
	return divisor;
    }

    public int gcd2(int a, int b) {
	if (b == 0) {
		return a;
	    }
	else if (a == 0) {
		return b;
	    }
	else {
	    int big,small;
	    if (a > b) {
		big = a;
		small = b;
	    }
	    else {
		big = b;
		small = a;
	    }
	    while (small > 1) {
		if (big % small != 0) {
		    int r;
		    r = big % small;
		    big = small;
		    small = r;
		}
		else {
		    return small;
		}
	    }
	    return small;
	}
    }

    //isPrime using while loop
    public boolean isPrime(int n) {
	int divisor;
	divisor = n-1;
	while (divisor >= 1) {
	    if (n%divisor == 0) {
		return divisor == 1;
	    }
	    else {
		divisor = divisor - 1;
	    }
	}
	return (divisor == 1);
    }

    //isPrime using for loop
    public boolean isPrimeFor(int n) {
	int divisor;
	for (divisor = n-1; n%divisor != 0; divisor -= 1) {
	    return (divisor == 1);
	}
	return (divisor == 1);
    }

}