I have nothing. I hate Diophantine equations. That is all I have to say today.

(edit) I came back to it after a 24 hour break. All that nonsense about scoring multiple results really took me in yesterday.

import 'dart:math';
import 'package:collection/collection.dart';

List<List<Point<int>>> getMachines(List<String> lines) => lines
    .splitBefore((e) => e == '')
    .map((m) => m
        .whereNot((e) => e.isEmpty)
        .map((l) => RegExp(r'(\d+)')
            .allMatches(l)
            .map((m) => int.parse(m.group(0)!))
            .toList())
        .map((pr) => Point(pr.first, pr.last))
        .toList())
    .toList();

bool isInteger(num n) => (n - n.round()).abs() < 0.00001;

int cost(Point a, Point b, Point goal) {
  var resA = (goal.x * b.y - goal.y * b.x) / (a.x * b.y - a.y * b.x);
  var resB = (a.x * goal.y - a.y * goal.x) / (a.x * b.y - a.y * b.x);
  return (isInteger(resA) && isInteger(resB))
      ? resA.round() * 3 + resB.round() * 1
      : 0;
}

int solve(mx, p) => [for (var m in mx) cost(m[0], m[1], m[2] + p)].sum;

const large = Point(10000000000000, 10000000000000);
part1(List<String> lines) => solve(getMachines(lines), Point(0, 0));
part2(List<String> lines) => solve(getMachines(lines), large);