Numbers

aloha.py

# Aloha number - number with all digits '4' or '7'
# Q - Given a number, find the aloha number just greater or equal to given number.
def alt(s):
  # print "Number: ", s
  if s == '4':
    return '7'
  elif s == '7':
    return '44'
  # s = str(n)
  i = s.find('8') if s.find('8') != -1 else s.find('9')
  if i == -1:
    new = toaloha(s)
    if new == s:
      new = toaloha(str(int(s) + 1))
    return new
  t = '4' * len(s[i:])
  x = '4' if s[:i] == '' else alt(s[:i])
  # print "T", x, t
  return x + t


def toaloha(s):
  # s = str(n)
  if (s.find('8') != -1) or (s.find('9') != -1):
    return alt(s)
  nu = [int(x) for x in s]
  fir = nu[0]
  if fir < 4:
    return '4' * len(s)
  elif fir == 4:
    return ('4' + toaloha(s[1:])) if len(nu) > 1 else '4'
  elif fir < 7:
    return '7' + '4' * (len(s) - 1)
  elif fir == 7:
    return ('7' + toaloha(s[1:])) if len(nu) > 1 else '7'
  else:
    return 'xyz'

if __name__ == '__main__':
  last = 0
  for i in range(10000):
    new = toaloha(str(i))
    try:
      assert(int(new) >= int(last))
    except AssertionError:
      print "Assertion failes", new, last, i
      exit(1)
    print i, new
    last = new