17 lines
503 B
Haskell
17 lines
503 B
Haskell
{-
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https://projecteuler.net/problem=2
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Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
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1, 2, 3, 5, 8, 13, 21, 34, 55, 89,...
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By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
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-}
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module Main where
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main :: IO ()
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main = print ans
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ans = sum $ filter even $ takeWhile(< 4_000_000) fibs
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fibs = 1 : 2 : zipWith (+) fibs (tail fibs)
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