bonus.py

def cat_n_times(s, n):
	print n*str(s)
	
	
def is_divisible_by_3(n):
	if n%3 == 0:	print "This number is divisible by 3."
	else:	print "This number is not divisible by 3."
		
		
def is_divisible_by_5(n):
	if n%5 == 0:	print "This number is divisible by 5."
	else:	print "This number is not divisible by 5."
	
	
def is_divisible_by_n(x, n):
	if x%n == 0:	print "Yes, {0} is divisible by {1}".format(x, n)
	else:	print "No, {0} is not divisible by {1}".format(x, n)


def sum_of_squares_of_digits(n):
    """
      >>> sum_of_squares_of_digits(1)
      1
      >>> sum_of_squares_of_digits(9)
      81
      >>> sum_of_squares_of_digits(11)
      2
      >>> sum_of_squares_of_digits(121)
      6
      >>> sum_of_squares_of_digits(987)
      194
    """
    return sum([int(i)**2 for i in str(n)])
    	

def dot_product(u, v):
    """
      >>> dot_product([1, 1], [1, 1])
      2
      >>> dot_product([1, 2], [1, 4])
      9
      >>> dot_product([1, 2, 1], [1, 4, 3])
      12
      >>> dot_product([2, 0, -1, 1], [1, 5, 2, 0])
      0
    """
    return sum([u[i]*v[i] for i in range(len(u))])
    
if __name__ == "__main__":
    import doctest
    print doctest.testmod()