Factorial

public class factorial
{
    public static int recursivo ( int n )
    {
        if( n<0 ) return 0;
        if( n<=1 ) return 1;
        return n*recursivo(n-1);
    }

    public static int iterativo ( int n )
    {
        if( n<0 ) return 0;
        if( n==0 ) return 1;
        for( int i=n-1 ; i>=2 ; i-- ) n*=i;
        return n;
    }
}