Recursion.java

public class Recursion {
	
	public static void findHome(int from) {
		if (from < 0) throw new IllegalArgumentException("from = " + from);
		
		if (from == 0) { //home = 0
			return;
		}
		
		findHome(from - 1);
	}
	
	public static int factorial(int n) {
		if (n < 0) throw new IllegalArgumentException("n = " + n);
		
		if (n == 0) {
			return 1;
		}
		
		return n * factorial(n - 1);
	}
	
	public static int factorialLoop(int n) {
		if (n < 0) throw new IllegalArgumentException("n = " + n);
		
		int p = 1;
		for (int i = 1; i <= n; i++) {
			p = p * i;
		}
		
		return p;
	}

	public static void main(String[] args) {
		int result;
		findHome(10);
		result = factorial(10);
		result = factorialLoop(10);
	}

}