day 10

src/aoc/Year2024/Day10.cs

@@ -1,20 +1,104 @@
+using aoc.Common;
+using MoreLinq;
+
 namespace aoc.Year2024;
 
-internal partial class Day10
+internal partial class Day10 // todo: common bfs?
 {
-    internal partial class Part1
-    {
-        public string Solve(string input)
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    internal partial class Part2
-    {
-        public string Solve(string input)
-        {
-            throw new NotImplementedException();
-        }
-    }
+	internal partial class Part1
+	{
+		private readonly Example example = new Example(
+			"""
+			89010123
+			78121874
+			87430965
+			96549874
+			45678903
+			32019012
+			01329801
+			10456732
+			""", 36);
+
+		public int Solve(int[,] input)
+		{
+			var trailHeads = input.AsEnumerable().Where(x => x.element == 0).ToArray();
+
+			return trailHeads.Sum(head =>
+			{
+				var list = new HashSet<V<int>>();
+				FillVisited(input, head.point, list);
+				return list.Count;
+			});
+		}
+
+		private static void FillVisited(int[,] map, V<int> curPos, HashSet<V<int>> list)
+		{
+			if (map.At(curPos) == 9)
+				list.Add(curPos);
+			var adj = new[]
+				{
+					Directions.Down(),
+					Directions.Up(),
+					Directions.Right(),
+					Directions.Left(),
+				}.Select(d => d + curPos)
+				.Where(map.Inside);
+
+			adj
+				.Where(p => map.At(p) == map.At(curPos) + 1)
+				.ForEach(p => FillVisited(map, p, list));
+		}
+
+		public int[,] Parse(string input)
+		{
+			return Character.Digit.Select(c => int.Parse(c.ToString()))
+				.Map().Parse(input);
+		}
+	}
+
+	internal partial class Part2
+	{
+		private readonly Example example = new(
+			"""
+			89010123
+			78121874
+			87430965
+			96549874
+			45678903
+			32019012
+			01329801
+			10456732
+			""", 81);
+
+		public int Solve(int[,] input)
+		{
+			var trailHeads = input.AsEnumerable().Where(x => x.element == 0).ToArray();
+
+			return trailHeads.Sum(head => Score(input, head.point));
+		}
+
+		private static int Score(int[,] map, V<int> curPos)
+		{
+			if (map.At(curPos) == 9)
+				return 1;
+			var adj = new[]
+				{
+					Directions.Down(),
+					Directions.Up(),
+					Directions.Right(),
+					Directions.Left(),
+				}.Select(d => d + curPos)
+				.Where(map.Inside);
+
+			return adj
+				.Where(p => map.At(p) == map.At(curPos) + 1)
+				.Sum(p => Score(map, p));
+		}
+
+		public int[,] Parse(string input)
+		{
+			return Character.Digit.Select(c => int.Parse(c.ToString()))
+				.Map().Parse(input);
+		}
+	}
 }

tests/AoC.Tests/InputTests.cs

@@ -26,5 +26,7 @@ private static IEnumerable<PartInputCaseData> GetCases()
 		yield return new PartInputCaseData(8, 2, "944");
 		yield return new PartInputCaseData(9, 1, "6279058075753");
 		yield return new PartInputCaseData(9, 2, "6301361958738");
+		yield return new PartInputCaseData(10, 1, "517");
+		yield return new PartInputCaseData(10, 2, "1116");
 	}
 }

tests/AoC.Tests/inputs/input10.txt

@@ -0,0 +1,45 @@
+123454078104569871014321021321012349878967874
+002965169245678562105489110456701256767456983
+411873254324329453456976522343812323454305432
+320984589010012306567887431098943210563216761
+458976673407873210698790346787654329874109850
+367887654356912348787891245497645698556780943
+656792343105401059678712312338562107649891234
+343001643234332769589600404329431236032321104
+102198756121049878465521565010120345121430213
+234567987012156912374437674320345034560345412
+126898776103457809983398983011276127672126703
+045678945434967618812287034567689018984035894
+034989876325898507600176127698548109123445665
+121070165016785216010165018345630678006510778
+015676234245234345323234509216721565217329889
+104389892104101059654965432101892674398456788
+010210743233298128760870123438984583212105998
+327805654654567637201256754347673294303614854
+476912348723498542112349861243100185454783763
+585210239010101443009659870652231256765692152
+694332108212012356788778778701645899801087001
+783445098302345653299894389614556732112396503
+612956789401298764108763210543678945013765412
+107810987567889655895654101012109876894894321
+016721076101910346781565092325012345765765010
+145432345234581232690478783234540332345654321
+298703876501698701541089654129651231056310145
+387212965012787650132108543098774340987234236
+456903454323456043236719612012589656891105687
+125876561210798101045898703343478797650112793
+034329870325887232784387643296556788943289832
+105610711456976545693211234187645019850176541
+612789804567803456789800105098732134567654320
+523898714326512101234764306789678325478956010
+630145625613456780345605219812569210329547854
+549234034702102395653216984503431678017632903
+678432129899801234764567893689120589098701012
+569562101234710109803891012778021432176512343
+450691032105676541012764569865434501089400154
+541782145694589132123453678345123671078321965
+432679238785410016787652101254010982361267873
+121018019856321125696545610763010973450398654
+038967025657689434545236789892129887650367743
+127652134768976521430129865430034796341459812
+234543089867987010321010178921015601232378103