24 lines
690 B
Standard ML
24 lines
690 B
Standard ML
fun isDecreasing (l: int list) : bool =
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ListPair.all (fn (a, b) => b < a andalso b >= a - 3) (l, tl l)
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fun isIncreasing (l: int list) : bool =
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ListPair.all (fn (a, b) => b > a andalso b <= a + 3) (l, tl l)
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val file = TextIO.openIn "day_2.txt"
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val input = TextIO.inputAll file;
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TextIO.closeIn file;
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val lines = String.tokens (fn (char) => char = #"\n") input
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val reports = map
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(fn (line) =>
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let val numbers = String.tokens Char.isSpace line
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in map (fn (n) => valOf (Int.fromString n)) numbers end
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)
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lines
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val safeReports = List.filter (fn (report) => isDecreasing report orelse isIncreasing report) reports
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val safeAmount = List.length safeReports
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