16 lines
597 B
Text
16 lines
597 B
Text
fun divisors(n: int): []int =
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filter (fn x => n%x == 0) (map (1+) (iota (n/2)))
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fun amicable((n: int, nd: int), (m: int, md: int)): bool =
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n < m && nd == m && md == n
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fun getPair (divs: [upper](int, int)) (flat_i: int): ((int,int), (int,int)) =
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let i = flat_i / upper
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let j = flat_i % upper
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in unsafe (divs[i], divs[j])
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fun main(upper: int): [][2]int =
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let range = map (1+) (iota upper)
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let divs = zip range (map (fn n => reduce (+) 0 (divisors n)) range)
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let amicable = filter amicable (map (getPair divs) (iota (upper*upper)))
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in map (fn (np,mp) => [#1 np, #1 mp]) amicable
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