Recursion

/**
 * This program will display the factorial for a number
 * CS 49
 * Hanzhuo Gong
 */
public class TestFactorial {

	public static void main(String[] args) {
		System.out.println("8!= " + UserfulRoutines.factorial(8));
		System.out.println("11!= " + UserfulRoutines.factorial(11));
		System.out.println("0!= " + UserfulRoutines.factorial(0));
		System.out.println("7!= " + UserfulRoutines.factorial(7));

	}

}

/**
 * Method for calculate the factorial number
 * CS 49
 * Hanzhuo Gong
 */
public class UserfulRoutines {
	public static long factorial(int num) {
		if (num < 0)
			return 0;
		if (num == 0)
			return 1;
		return factorial(num-1)*num;

	}

}

/*------------------------------output---------------------------
8!= 40320
11!= 39916800
0!= 1
7!= 5040 
*/