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20 lines
452 B
Elm
20 lines
452 B
Elm
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module CollatzConjecture exposing (collatz)
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collatz : Int -> Result String Int
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collatz start =
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if start <= 0 then
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Err "Only positive numbers are allowed"
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else
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Ok (collatzHelper 0 start)
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collatzHelper : Int -> Int -> Int
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collatzHelper steps start =
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if start == 1 then
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steps
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else if start % 2 == 0 then
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collatzHelper (1 + steps) (start // 2)
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else
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collatzHelper (1 + steps) (3 * start + 1)
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