41 lines
901 B
Nix
41 lines
901 B
Nix
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{ pkgs, lib }:
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with lib;
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let
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input = pipe (fileContents ./input.txt) [
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(splitString "\n")
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(map (split "[[:space:]]+"))
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(map (filter (x: x != [])))
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(map (map toInt))
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];
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# - The levels are either all increasing or all decreasing.
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# - Any two adjacent levels differ by at least one and at most three.
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safeCondition = xs: let
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zipped = zipLists xs (tail xs);
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in (all ({ fst, snd }: let x = fst - snd; in 1 <= x && x <= 3) zipped)
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|| (all ({ fst, snd }: let x = fst - snd; in -1 >= x && x >= -3) zipped);
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answer1 = lib.pipe input [
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(filter safeCondition)
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length
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toString
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];
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answer2 = lib.pipe input [
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(filter (xs: let
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variants = genList (i: (take i xs) ++ (drop (i + 1) xs)) (length xs);
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in any safeCondition variants))
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length
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toString
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];
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in
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pkgs.writeText "answers" ''
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Task1:
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${answer1}
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Task2:
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${answer2}
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''
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