AOC2020/aoc2020/lib/aoc20201205.dart

import 'dart:math';
import 'package:aoc2020/aocbase.dart';
import 'package:aoc2020/model/point.dart';
import 'package:aoc2020/model/readdata.dart';

class AOC20201205 extends AOCBase {
  Point calcSeat(String row) {
    var rmax = 127;
    var cmax = 7;
    for (var rowBin = 0; rowBin < 7; rowBin++) {
      var range = 128 >> rowBin + 1;
      rmax -= (row[rowBin] == 'F') ? range : 0;
    }
    for (var rowBin = 0; rowBin < 3; rowBin++) {
      var range = 8 >> rowBin + 1;
      cmax -= (row[rowBin + 7] == 'L') ? range : 0;
    }
    return Point(rmax, cmax);
  }

  @override
  Future<void> a({bool test}) async {
    var mylist = await ReadData.readFile<String>(classString, test: test);
    var maxSeatId = 0;
    for (var row in mylist) {
      var seat = calcSeat(row);
      var val = seat.item1 * 8 + seat.item2;
      maxSeatId = max(maxSeatId, val);
    }
    answerA = maxSeatId;
  }

  @override
  Future<void> b({bool test}) async {
    var mylist = await ReadData.readFile<String>(classString, test: test);
    var plane = List.generate(128, (i) => List.generate(8, (j) => false, growable: false), growable: false);

    for (var row in mylist) {
      var seat = calcSeat(row);
      plane[seat.item1][seat.item2] = true;
    }

    for (var rowIndex = 0; rowIndex < plane.length; rowIndex++) {
      var row = plane[rowIndex];
      if (row[0] == false) continue;
      if (row.contains(false)) {
        var column = row.indexWhere((seat) => seat == false);
        answerB = rowIndex * 8 + column;
        return;
      }
    }
  }
}