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cpfiffer/P21.hs

Created March 25, 2018 16:32
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Solves problem 21 of Project Euler with list comprehensions.
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P21.hs
module P21 (properDivisors, sumDivisors, sumAmicable, isAmicable, amicableList) where
properDivisors :: Int -> [Int]
properDivisors x = [xs | xs <- [1..x-1], x `mod` xs == 0]
sumDivisors :: Int -> Int
sumDivisors x = sum $ properDivisors x
sumAmicable = sum [x | x <- [1..10000], isAmicable x]
amicableList = [x | x <- [1..10000], isAmicable x]
isAmicable x = if sumDivisors otherNumber == x && not (x == otherNumber) then True else False
where otherNumber = sumDivisors x
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