Add day 10

AdventOfCode2024.sln

@@ -21,6 +21,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Day8", "Day8\Day8.csproj",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Day9", "Day9\Day9.csproj", "{E343E757-5AAC-4CDC-9B78-A5FB2466DAE2}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Day10", "Day10\Day10.csproj", "{9DA97BBA-99AF-4FA7-97BB-C6EF3F8B24A4}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -63,6 +65,10 @@ Global
 		{E343E757-5AAC-4CDC-9B78-A5FB2466DAE2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{E343E757-5AAC-4CDC-9B78-A5FB2466DAE2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{E343E757-5AAC-4CDC-9B78-A5FB2466DAE2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9DA97BBA-99AF-4FA7-97BB-C6EF3F8B24A4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9DA97BBA-99AF-4FA7-97BB-C6EF3F8B24A4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9DA97BBA-99AF-4FA7-97BB-C6EF3F8B24A4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9DA97BBA-99AF-4FA7-97BB-C6EF3F8B24A4}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

Day10/Day10.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <None Update="input.txt">
+        <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      </None>
+    </ItemGroup>
+
+</Project>

Day10/Program.cs

@@ -0,0 +1,142 @@
+var rawTopographicMap = File.ReadLines("input.txt");
+var topographicMap = CreateTopographicMap(rawTopographicMap);
+
+var availableDirections = new List<(int, int)>()
+{
+    (-1, 0), // Up
+    (1, 0), // Down
+    (0, -1), // Left
+    (0, 1) // Right
+};
+
+Console.WriteLine($"Part1: {Part1(topographicMap, availableDirections)}\nPart2: {Part2(topographicMap, availableDirections)}");
+
+
+int Part2(int[,] mapInput, List<(int, int)> directions)
+{
+    var totalRating = 0;
+    for (var r = 0; r < mapInput.GetLength(0); r++)
+    {
+        for (var c = 0; c < mapInput.GetLength(1); c++)
+        {
+            if (mapInput[r, c] == 0)
+            {
+                totalRating += FindDistinctTrails(r, c, mapInput, directions);
+            }
+        }
+    }
+
+    return totalRating;
+}
+
+int FindDistinctTrails(int r, int c, int[,] mapInput, List<(int, int)> directions)
+{
+    var stack = new Stack<List<(int, int)>>();
+    stack.Push(new List<(int, int)> { (r, c) });
+    var trails = 0;
+
+    while (stack.Count > 0)
+    {
+        var currentPath = stack.Pop();
+        var (cr, cc) = currentPath[^1];
+        
+        if (mapInput[cr, cc] == 9)
+        {
+            trails++;
+            continue;
+        }
+
+        foreach (var (dr, dc) in directions)
+        {
+            var nr = cr + dr;
+            var nc = cc + dc;
+            
+            if (nr >= 0 && nr < mapInput.GetLength(0) && nc >= 0 && nc < mapInput.GetLength(1) &&
+                mapInput[nr, nc] == mapInput[cr, cc] + 1)
+            {
+                var nextPath = new List<(int, int)>(currentPath);
+                nextPath.Add((nr, nc));
+                stack.Push(nextPath);
+            }
+        }
+    }
+
+    return trails;
+}
+
+int Part1(int[,] map, List<(int, int)> directions)
+{
+    var totalScore = 0;
+
+    for (var row = 0; row < map.GetLength(0); row++)
+    {
+        for (var column = 0; column < map.GetLength(1); column++)
+        {
+            if (map[row, column] == 0)
+            {
+                totalScore += TrailHead(row, column, map, directions);
+            }
+        }
+    }
+
+    return totalScore;
+}
+
+int TrailHead(int startRow, int startColumn, int[,] map, List<(int, int)> directions)
+{
+    var rows = map.GetLength(0);
+    var cols = map.GetLength(1);
+    var queue = new Queue<(int, int)>();
+    var visited = new HashSet<(int, int)>();
+    var reachableNines = new HashSet<(int, int)>();
+
+    queue.Enqueue((startRow, startColumn));
+
+    while (queue.Count > 0)
+    {
+        var (r, c) = queue.Dequeue();
+
+        if (visited.Contains((r, c)))
+            continue;
+
+        visited.Add((r, c));
+
+        if (map[r, c] == 9)
+        {
+            reachableNines.Add((r, c));
+            continue;
+        }
+
+        foreach (var dir in directions)
+        {
+            var nr = r + dir.Item1;
+            var nc = c + dir.Item2;
+
+            if (nr >= 0 && nr < rows && nc >= 0 && nc < cols)
+            {
+                if (map[nr, nc] == map[r, c] + 1)
+                {
+                    queue.Enqueue((nr, nc));
+                }
+            }
+        }
+    }
+
+    return reachableNines.Count;
+}
+
+int[,] CreateTopographicMap(IEnumerable<string> lines)
+{
+    var lineList = lines.Select(line => line.Trim()).ToList();
+    var map = new int[lineList.Count, lineList[0].Length];
+
+    for (var r = 0; r < map.GetLength(0); r++)
+    {
+        for (var c = 0; c < map.GetLength(1); c++)
+        {
+            map[r, c] = lineList[r][c] - '0';
+        }
+    }
+
+    return map;
+}

Day10/input.txt

@@ -0,0 +1,48 @@
+101987698323656762989721011010987456780121243210
+234012567210547891078892012101072345891030984569
+142103454345432012367743423232161654322345855678
+051054965236701103456656894343450783210496764789
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+657857762876567610765100340101238763210798545692
+765446891001498723834232215293045678189877632781
+802335432312387654923341004382167669012368701020
+911124701421019870110056905673458978975459345210
+320099876598943065232167810569898963287561276349
+456787756787854104343054321678107854196510389458
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+965678798523470189630141043454387011055432108912
+234309657631063238745632658965296545765443297983
+103210545432154127030745667870101239812344589854
+123451236943061032121836789654320149801256678765
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+549831009871234534328323763011017632176548902369
+038742789965676548933214892182126543210423098454
+125653656234987837654300321099234304321012167823
+034564540165832921020311456788765015698143456910
+321078939874981021011232321001298923789874301501
+012981543403876120102345409876387654301565217652
+565470034512985433201456912345401543214321438943
+678321127621076894398567810126918754265410521032
+099128938902345765487656787637829662178345621001
+187019878213765496567678698540134543089210782789
+236520569347874385438569187687238956745432893610
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+876532321876101301210321149823456721949890765434
+765321012765432340343434231012545430132101256545