adventofcode2025/lib/day4/command.dart

import "dart:convert";
import "dart:io";

import "package:args/command_runner.dart";

List getAdjacent(List<List<bool>> map, int idx, int idy) {
  var adjacentValues = [];
  for (int x in [-1, 0, 1]) {
    for (int y in [-1, 0, 1]) {
      if (x == 0 && y == 0) {
        continue;
      }
      var xSlewed = idx + x;
      var ySlewed = idy + y;
      //print("$xSlewed, $ySlewed");
      try {
        //print(map[ySlewed][xSlewed]);
        adjacentValues.add(map[ySlewed][xSlewed]);
      } on RangeError {
        continue;
      }
    }
  }
  return adjacentValues;
}

(int, List<List<bool>>) removeRolls(List<List<bool>> rollMap) {
  int rollsRemoved = 0;
  List<List<bool>> newRollMap = List.from(
    rollMap.map((e) => List<bool>.from(e, growable: false)),
    growable: false,
  );
  for (var (y, row) in rollMap.indexed) {
    for (var (x, columnValue) in row.indexed) {
      if (columnValue == true) {
        var numAdjacent = getAdjacent(
          rollMap,
          x,
          y,
        ).where((value) => value).length;
        if (numAdjacent < 4) {
          rollsRemoved++;
          newRollMap[y][x] = false;
        }
      }
    }
  }
  return (rollsRemoved, newRollMap);
}

class Day4Command extends Command {
  // The [name] and [description] properties must be defined by every
  // subclass.
  @override
  final name = "day4";

  @override
  final description = "Run Advent of Code 2025 Day 4";

  Day4Command() {
    // we can add command specific arguments here.
    // [argParser] is automatically created by the parent class.
  }

  // [run] may also return a Future.
  @override
  Future<void> run() async {
    // [argResults] is set before [run()] is called and contains the flags/options
    // passed to this command.

    if (argResults!.rest.length != 1) {
      print(
        "Expected 1 positional arguments, found ${argResults!.rest.length}",
      );
      exit(1);
    }
    var filePath = argResults!.rest[0];

    print("Parsing file: $filePath");
    var inputFile = File(filePath);
    var paperRollMap = await inputFile
        .openRead()
        .transform(utf8.decoder)
        .transform(LineSplitter())
        .map((line) {
          return line
              .split('')
              .map((ch) => (ch == "@") ? true : false)
              .toList(growable: false);
        })
        .toList();
    //print(paperRollMap);
    //print(getAdjacent(paperRollMap, 0, 0));

    int round = 1;
    int totalRollsRemoved = 0;
    while (true) {
      int rollsRemoved;
      (rollsRemoved, paperRollMap) = removeRolls(paperRollMap);
      print("Rolls Removed During Round $round: $rollsRemoved");
      if (rollsRemoved == 0) {
        break;
      }
      totalRollsRemoved += rollsRemoved;
      round++;
    }
    print("Total Rolls Removed: $totalRollsRemoved");
  }
}