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# 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])
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