Python reply to https://extras.waynewbishop.com/challenge/power-of-two

power_of_two.py

def is_power_of_two(an_int):
  # We use the binary representation to work with
  bits = bin(an_int)[2:] # truncates the "0b" part of the string
  # A power of two only has one bit set, so the sum of all bits needs to be 1
  return sum([int(x) for x in list(bits)]) == 1 

def is_power_of_two_recursive(an_int):
  if an_int < 0:
    return is_power_of_two_recursive(-an_int)
  elif an_int == 0:
    return False
  elif an_int == 1:
    return True
  else:
    # recursive, with early bailout if there is a non-divisible by two part
    return an_int % 2 == 0 and is_power_of_two_recursive(an_int//2)