Today’s problem had to do with Happy Numbers.

I split the problem up in two parts, splitting up a number up in to digits and checking whether or not the number is a Happy Number.

The first part I implemented in two different ways.

Method 1:

def chop(x):
  r = []
  length = int(ceil(log(x, 10)))
  if ceil(log(x, 10)) == int(ceil(log(x, 10))):
    length += 1
  #a(dd), s(ubstract)
  for a,s in zip(range(0, length), range(length-1, -1, -1)):
    temp = x/(10**s)
    for i,e in enumerate(r):
      temp -= e * 10**(len(r)-i)
  return r

Method 2:

def chop2(x):
  return [int(x) for x in str(x)]

Method 2 is shorter and faster, but I really wanted to try solving it by just using numbers. String conversions feel a bit “dirty”.

Then finally, checking whether a number is a happy number or not:

def isHappyNumber(x):
  if x <= 0:
    return False
  numbers = [x]
  while x != 1:
    x = sum([a**2 for a in chop(x)])
    if x in numbers:
      return False
  return True

The source can also be found on Bitbucket.