53 lines
1.3 KiB
Nix
53 lines
1.3 KiB
Nix
{lib, ...}: let
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inherit (builtins) stringLength concatLists substring foldl' add attrValues;
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inherit (lib.strings) toIntBase10;
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in input: rec {
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blinkStone = stone: count:
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if toIntBase10 stone == 0 then [{ "1" = count; }]
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else let
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strStone = toString (toIntBase10 stone);
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len = stringLength strStone;
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left = (substring 0 (len / 2) strStone );
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right = (substring (len / 2) (len / 2) strStone);
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in
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if lib.mod len 2 == 0 then
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if left == right then [{${left} = count * 2;}] else [
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{ ${left} = count; ${right} = count; }
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]
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else [{
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${toString ((toIntBase10 stone) * 2024)} = count;
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}]
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;
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bfast = stones: stones
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|> (builtins.mapAttrs (stone: blinkStone stone))
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|> attrValues
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|> concatLists
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|> addStones
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;
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bfastt = times: stones:
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if times == 0 then stones |> attrValues |> foldl' add 0
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else bfastt (times - 1) (bfast stones)
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;
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addStones = builtins.zipAttrsWith (stone: foldl' add 0);
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initialStones = input
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|> lib.trim
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|> lib.splitString " "
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|> map toIntBase10
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|> toStones
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;
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toStones = numbers: numbers
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|> map (number: {name = toString number; value = 1;})
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|> builtins.listToAttrs
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;
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part1result = bfastt 25 initialStones;
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part2result = bfastt 75 initialStones;
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}
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