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ncfavier/p208.hs

Last active June 17, 2023 09:16
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p208.hs
{-# LANGUAGE LambdaCase, BlockArguments, ViewPatterns #-}
import Data.MemoTrie
count :: [Int] -> Int
count = memoFix \ go -> \case
[0, 0, 0, 0, 0] -> 1
[a, b, c, d, e] -> sum $ [go [b, c, d, e, a - n] | n <- [1,3..a]]
<> [go [e, d, c, b, a - n] | n <- [2,4..a]]
main = print $ 2 * count (replicate 5 14)
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