The reindeer's symptoms are getting worse, and neither you nor the white-bearded man have a solution. At least the reindeer has a warm place to rest: a small bed near where you're sitting.

As you reach down, the reindeer looks up at you, accidentally bumping a button on your wrist-mounted device with its nose in the process - a button labeled "help".

Read the full puzzle.

using System;
using System.Collections.Generic;
using System.Linq;

namespace AdventOfCode.Y2018.Day25;

[ProblemName("Four-Dimensional Adventure")]
class Solution : Solver {

    public object PartOne(string input) {
        var sets = new List<HashSet<int[]>>();

        foreach (var line in input.Split("\n")) {
            var set = new HashSet<int[]>();
            set.Add(line.Split(",").Select(int.Parse).ToArray());
            sets.Add(set);
        }

        foreach (var set in sets.ToList()) {
            var pt = set.Single();
            var closeSets = new List<HashSet<int[]>>();
            foreach (var setB in sets) {
                foreach (var ptB in setB) {
                    if (Dist(pt, ptB) <= 3) {
                        closeSets.Add(setB);
                    }
                }
            }
            var mergedSet = new HashSet<int[]>();
            foreach (var setB in closeSets) {
                foreach (var ptB in setB) {
                    mergedSet.Add(ptB);
                }
                sets.Remove(setB);
            }
            sets.Add(mergedSet);
        }

        return sets.Count;
    }
   
    int Dist(int[] a, int[] b) => Enumerable.Range(0, a.Length).Select(i => Math.Abs(a[i] - b[i])).Sum();

}

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