46 lines
1.6 KiB
Nix
46 lines
1.6 KiB
Nix
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let
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# Import nixpkgs lib and input file
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inherit ((builtins.getFlake (builtins.toString ./..)).inputs.nixpkgs) lib;
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input = builtins.readFile (builtins.toString ./input.txt);
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# Do parsing
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parsed = ( # Define function to sort lines into two lists
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lib.lists.foldr
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(cur: acc: {
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first = acc.first ++ [(lib.strings.toIntBase10 (builtins.elemAt cur 0))];
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second = acc.second ++ [(lib.strings.toIntBase10 (builtins.elemAt cur 1))];
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})
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{ first = []; second = []; }
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) ( # Call with input split on newlines and 3 spaces; formatted like [ [ 1 2 ] [ 3 4 ] [ 5 6 ] ]
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lib.lists.forEach
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(lib.strings.splitString "\n" input)
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(e: lib.strings.splitString " " e)
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);
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collapsed = (
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lib.lists.foldr
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(cur: acc:
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acc // (
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if (builtins.hasAttr "${builtins.toString cur}" acc)
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then {
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"${builtins.toString cur}" = acc."${builtins.toString cur}" + 1;
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}
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else {
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"${builtins.toString cur}" = 1;
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}
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)
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)
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{}
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) parsed.second;
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output = (
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lib.lists.foldr
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(cur: acc:
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acc + (
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if (builtins.hasAttr "${builtins.toString cur}" collapsed)
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then (cur * collapsed."${builtins.toString cur}")
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else 0
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)
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)
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0
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) parsed.first;
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in output
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