commit 322293f2005441ba2715174a29346c3450403bc2 · dunkirk.sh/aoc-2025

README.md

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       This contains my solutions to advent of code 2025 in mostly `ts` or `nix` depending on how lazy I'm feeling that day.

     

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       The main repo is [the tangled repo](https://tangled.org/dunkirk.sh/aoc-2025) and the github is just a mirror.

     

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       <p align="center">

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       This contains my solutions to advent of code 2025 in mostly `ts` or `nix` depending on how lazy I'm feeling that day.

     

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       ```bash

     

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       bun run index.ts

     

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       nix-instantiate --eval --strict solution.nix

     

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       ```

     

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       The main repo is [the tangled repo](https://tangled.org/dunkirk.sh/aoc-2025) and the github is just a mirror.

     

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       <p align="center">

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nix/01/input.txt

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nix/01/solution.nix

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       let

     

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         input = builtins.readFile ./input.txt;

     

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         lines = builtins.filter (s: builtins.isString s && s != "") (builtins.split "\n" input);

     

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         mod = a: b: a - (a / b) * b;

     

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         part1 = 

     

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           let

     

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             processLine = state: line:

     

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               let

     

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                 dir = builtins.substring 0 1 line == "R";

     

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                 num = builtins.fromJSON (builtins.substring 1 (builtins.stringLength line - 1) line);

     

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                 newDial = mod (if dir then state.dial + num else state.dial - num + 100) 100;

     

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               in {

     

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                 dial = newDial;

     

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                 count = state.count + (if newDial == 0 then 1 else 0);

     

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               };

     

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             result = builtins.foldl' processLine { dial = 50; count = 0; } lines;

     

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           in result.count;

     

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         part2 =

     

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           let

     

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             processLine = state: line:

     

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               let

     

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                 dir = builtins.substring 0 1 line;

     

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                 num = builtins.fromJSON (builtins.substring 1 (builtins.stringLength line - 1) line);

     

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                 dialBefore = state.dial;

     

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                 distToZero = 

     

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                   let raw = if dir == "R" then mod (100 - dialBefore) 100 else mod dialBefore 100;

     

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                   in if raw == 0 then 100 else raw;

     

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                 passCount = if num >= distToZero then 1 + (num - distToZero) / 100 else 0;

     

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                 newDial = 

     

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                   let d = if dir == "R" 

     

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                           then mod (dialBefore + num) 100 

     

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                           else mod (100 + dialBefore - (mod num 100)) 100;

     

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                   in mod (100 + d) 100;

     

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               in {

     

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                 dial = newDial;

     

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                 count = state.count + passCount;

     

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               };

     

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             result = builtins.foldl' processLine { dial = 50; count = 0; } lines;

     

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           in result.count;

     

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       in {

     

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         inherit part1 part2;

     

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       }