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18 lines
381 B
Plaintext
18 lines
381 B
Plaintext
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use Nat drop
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use Optional None Some
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search : (Nat -> Int) -> Nat -> Nat -> Optional Nat
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search hit bot top =
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go : Nat -> Nat -> Optional Nat
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go bot top =
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if bot >= top then None
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else
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mid = (bot + top) / 2
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match hit mid with
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+0 -> Some mid
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-1 -> go bot (drop mid 1)
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+1 -> go (mid + 1) top
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_ -> bug "unexpected"
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go bot top
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