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45 lines
2.0 KiB
Plaintext
45 lines
2.0 KiB
Plaintext
app [main] {
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pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.17.0/lZFLstMUCUvd5bjnnpYromZJXkQUrdhbva4xdBInicE.tar.br",
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}
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import pf.Stdout
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import "data.txt" as data : Str
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main =
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lines = Str.splitOn data "\n" |> List.dropLast 1
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levels = List.map lines \l -> Str.splitOn l " " |> List.keepOks Str.toU8
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part1 = List.keepIf levels \l -> isSafe l Bool.false
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Stdout.line! "Safe Reports, Part 1: $(Num.toStr (List.len part1))"
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# my algorithm doesn't work great with tolerating the first or 2nd elements, so just run it again with those elements dropped and no dampening
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part2 = List.keepIf levels \l -> (isSafe l Bool.true) || (isSafe (List.dropAt l 0) Bool.false) || (isSafe (List.dropAt l 1) Bool.false)
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Stdout.line! "Safe Reports, Part 2: $(Num.toStr (List.len part2))"
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isSafe = \line, isDampening ->
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List.walkWithIndexUntil line { value: 0, direction: Unset, valid: Bool.true, skipped: 0 } \state, value, idx ->
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if idx == 0 then # on first iteration, can't fail, just return
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Continue { state & value, direction: Unset }
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else
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diff = Num.absDiff value state.value
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if diff < 1 || diff > 3 then # always check diff
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if isDampening && state.skipped == 0 then
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Continue { state & skipped: 1 }
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else
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Break { state & valid: Bool.false }
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else
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direction = if value > state.value then Ascending else Descending
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if idx == 1 then # on 2nd iteration, we don't check for direction change
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Continue { state & value, direction }
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else if state.direction != direction then
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if isDampening && state.skipped == 0 then
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Continue { state & skipped: 1 }
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else
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Break { state & valid: Bool.false }
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else
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Continue { state & value, direction }
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|> .valid
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