isKaprekarNumber.py

# Solution to [2016-10-31] Challenge #290 [Easy] Kaprekar Numbers
# found at https://www.reddit.com/r/dailyprogrammer/comments/5aemnn/20161031_challenge_290_easy_kaprekar_numbers/

def isKaprekar(number):
    '''
    Tests every number in range for being a Kaprekar number as defined at
    https://en.wikipedia.org/wiki/Kaprekar_number
    '''
    squared = number ** 2
    str_squared = str(squared)

    if len(str_squared) == 1 and number > 0:
        return True if squared == number else False


    for i in range(1, len(str_squared)):
        first = int(str_squared[:i])
        second = int(str_squared[i:])
        if first == 0 or second == 0:
            continue
        if first + second == number:
            return True

    return False


def kaprekarsInRange(start, end):
    '''
        param start: integer
        param end: integer, included in the range of tested numbers
        Returns a list of kaprekars numbers in the range.
    '''

    kaprekars = []
    for num in range(start, end+1):
        if isKaprekar(num):
            kaprekars.append(num)

    return kaprekars

# Test
print(kaprekarsInRange(0, 100000) == [1, 9, 45, 55, 99, 297, 703, 999, 2223, 2728, 4879, 4950, 5050, 5292, 7272, 7777, 9999, 17344, 22222, 38962, 77778, 82656, 95121, 99999])