benharri.org
my advent of code solutions
1namespace Solutions._2018;
2
3/// <summary>
4/// Day 2: <a href="https://adventofcode.com/2018/day/2"/>
5/// </summary>
6public sealed class Day02InventoryManagementSystem() : Day(2018, 2, "Inventory Management System")
7{
8 private static bool HasNChars(string line, int count)
9 {
10 for (var i = 'a'; i <= 'z'; i++)
11 if (line.Count(c => c == i) == count)
12 return true;
13
14 return false;
15 }
16
17 public override object Part1() =>
18 Input.Count(l => HasNChars(l, 2)) * Input.Count(l => HasNChars(l, 3));
19
20 public override object Part2()
21 {
22 var input = Input.ToImmutableList();
23
24 foreach (var id1 in input)
25 foreach (var id2 in input.Where(line2 => id1.HammingDistance(line2) == 1))
26 return id1.Remove(id1.Zip(id2).Indexed().First(i => i.Value.First != i.Value.Second).Key, 1);
27
28 throw new("Correct IDs not found");
29 }
30}