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AnthonyMikh/noThreeOnes.hs

Created February 23, 2018 17:52
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Решение задачи №73 от UniLecs
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noThreeOnes.hs
tribonacci = 0:0:1:zipWith3 (\x y z -> x+y+z) tribonacci (tail tribonacci) (drop 2 tribonacci)
solutions = 0:drop 4 tribonacci
solution = (solutions !!)
main = print . solution $ 4 -- 13
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Playground: https://repl.it/repls/AdmiredSkeletalDisassembly

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AnthonyMikh commented Feb 23, 2018 •
edited
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Обоснование решения (сравнение с решением "в лоб"):

seed = ["00", "01", "10", "11"]

advanseSeq list@(x:y:_) = case (x, y) of
    ('1', '1') -> ['0':list]
    _ -> ['0':list, '1':list]

advanse = concatMap advanseSeq

solutions = iterate advanse seed

lens = 0:2:map length solutions

tribonacci = 0:0:1:zipWith3 (\x y z -> x+y+z) tribonacci (tail tribonacci) (tail . tail $ tribonacci)

lens2 = 0:drop 4 tribonacci

main = print . take 15 $ zipWith (==) lens lens2

Вывод:

[True,True,True,True,True,True,True,True,True,True,True,True,True,True,True]

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