The Elves managed to locate the chimney-squeeze prototype fabric for Santa's suit (thanks to someone who helpfully wrote its box IDs on the wall of the warehouse in the middle of the night). Unfortunately, anomalies are still affecting them - nobody can even agree on how to cut the fabric.

The whole piece of fabric they're working on is a very large square - at least 1000 inches on each side.

Read the full puzzle.

using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCode.Y2018.Day03;

[ProblemName("No Matter How You Slice It")]
class Solution : Solver {

    public object PartOne(string input) => Decorate(input).overlapArea;

    public object PartTwo(string input) => Decorate(input).intactId;

    (int overlapArea, int intactId) Decorate(string input) {
        // #1 @ 55,885: 22x10
        var rx = new Regex(@"(?<id>\d+) @ (?<x>\d+),(?<y>\d+): (?<width>\d+)x(?<height>\d+)");
        var mtx = new int[1000, 1000];

        var overlapArea = 0;

        var ids = new HashSet<int>();
        foreach (var line in input.Split("\n")) {
            var parts = rx.Match(line);
            var id = int.Parse(parts.Groups["id"].Value);
            var x = int.Parse(parts.Groups["x"].Value);
            var y = int.Parse(parts.Groups["y"].Value);
            var width = int.Parse(parts.Groups["width"].Value);
            var height = int.Parse(parts.Groups["height"].Value);

            ids.Add(id);

            for (var i = 0; i < width; i++) {
                for (var j = 0; j < height; j++) {
                    if (mtx[x + i, y + j] == 0) {
                        mtx[x + i, y + j] = id;
                    } else if (mtx[x + i, y + j] == -1) {
                        ids.Remove(id);
                    } else {
                        ids.Remove(mtx[x + i, y + j]);
                        ids.Remove(id);
                        overlapArea++;

                        mtx[x + i, y + j] = -1;
                    }
                }
            }
        }

        return (overlapArea, ids.Single());
    }
}

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