Initial Commit

2024/Day04CSharp/Program.cs

@@ -0,0 +1,197 @@
+var exParsed = new Day04Parsed("example-input.txt");
+
+Console.WriteLine("Example Part01: {0}", exParsed.GetPart01());
+Console.WriteLine("Example Part02: {0}", exParsed.GetPart02());
+
+var pzParsed = new Day04Parsed("puzzle-input.txt");
+
+Console.WriteLine("Puzzle Part01: {0}", pzParsed.GetPart01());
+Console.WriteLine("Puzzle Part02: {0}", pzParsed.GetPart02());
+
+class Day04Parsed : AdventCommon.ParsedInput
+{
+    static readonly string WORD_TO_SEARCH = "XMAS";
+
+    List<string> letterGrid = new List<string>();
+
+    public Day04Parsed(string fileName) : base(fileName)
+    {
+    }
+
+    public override int GetPart01()
+    {
+        int count = 0;
+
+        for (int i = 0; i < letterGrid.Count; i++)
+        {
+            var row = GetRow(i);
+
+            for (int j = 0; j < row.Length; j++)
+            {
+                var words = GetWords(i, j);
+                count += CountWords(words, WORD_TO_SEARCH);
+            }
+        }
+
+        return count;
+    }
+
+    public override int GetPart02()
+    {
+        int count = 0;
+
+        for (int i = 0; i < letterGrid.Count; i++)
+        {
+            var row = GetRow(i);
+            for (int j = 0; j < row.Length; j++)
+            {
+                if (IsMASX(i, j)) { count++; }
+            }
+        }
+
+        return count;
+    }
+
+    public bool IsMASX(int i, int j)
+    {
+        try
+        {
+            string wordToSearch = "MAS";
+            string rwordToSearch = new string(wordToSearch.Reverse().ToArray());
+
+            if (GetEntry(i,j) != 'A') { return false; }
+
+            string backwardSlash = String.Format("{0}{1}{2}", GetEntry(i-1,j-1), GetEntry(i,j), GetEntry(i+1,j+1));
+            string forwardSlash = String.Format("{0}{1}{2}", GetEntry(i-1,j+1), GetEntry(i,j), GetEntry(i+1,j-1));
+
+            if (    (String.Compare(backwardSlash, wordToSearch) == 0 || String.Compare(backwardSlash, rwordToSearch) == 0)
+                &&  (String.Compare(forwardSlash, wordToSearch) == 0 || String.Compare(forwardSlash, rwordToSearch) == 0))
+            {
+                return true;
+            }
+        } 
+        catch (Exception) { }
+
+        return false;
+    }
+
+    string GetRow(int i) => letterGrid[i];
+    string GetColumn(int i) {
+        string toRet = "";
+        foreach (var line in letterGrid)
+        {
+            toRet += line[i];
+        }
+        return toRet;
+    }
+
+    char GetEntry(int i, int j) => letterGrid[i][j];
+
+    static int CountWords(List<string> words, string wordToSearch)
+    {
+        int count = 0;
+
+        string rwordToSearch = new string(wordToSearch.Reverse().ToArray());
+
+        foreach (var word in words)
+        {
+            if (String.Compare(word, wordToSearch) == 0 || String.Compare(word, rwordToSearch) == 0)
+            {
+                count++;
+            }
+        }
+
+        return count;
+    }
+
+    List<string> GetWords(int i, int j)
+    {
+        List<string> words = new List<string>();
+
+        // Scan only with X
+        if (GetEntry(i, j) != 'X')
+        {
+            return words;
+        }
+
+        var row = GetRow(i);
+        var col = GetColumn(j);
+
+        // Get horizontal
+        try
+        {
+            words.Add(row.Substring(j, WORD_TO_SEARCH.Length));
+        } catch (Exception) { }
+
+        // Get backwards
+        try
+        {
+            words.Add(row.Substring(j-(WORD_TO_SEARCH.Length-1), WORD_TO_SEARCH.Length));
+        } catch (Exception) { }
+
+        // Get vertical down
+        try
+        {
+            words.Add(col.Substring(i, WORD_TO_SEARCH.Length));
+        } catch (Exception) { }
+
+        // Get vertical "up"
+        try
+        {
+            words.Add(col.Substring(i-(WORD_TO_SEARCH.Length-1), WORD_TO_SEARCH.Length));
+        } catch (Exception) { }
+
+        // Top Right Diag
+        try
+        {
+            string diag = "";
+            for (int x = i, y = j; y < j+WORD_TO_SEARCH.Length; x--, y++)
+            {
+                diag += GetEntry(x, y);
+            }
+            words.Add(diag);
+        } catch (Exception) { }
+
+        // Down right Diag
+        try
+        {
+            string diag = "";
+            for (int x = i, y = j; y < j + WORD_TO_SEARCH.Length; x++, y++)
+            {
+                diag += GetEntry(x, y);
+            }
+            words.Add(diag);
+        } catch (Exception) { }
+
+        // Down left Diag
+        try
+        {
+            string diag = "";
+            for (int x = i, y = j; y > j - WORD_TO_SEARCH.Length; x++, y--)
+            {
+                diag += GetEntry(x, y);
+            }
+            words.Add(diag);
+        } catch (Exception) { }
+
+        // Up right Diag
+        try
+        {
+            string diag = "";
+            for (int x = i, y = j; y > j - WORD_TO_SEARCH.Length; x--, y--)
+            {
+                diag += GetEntry(x, y);
+            }
+            words.Add(diag);
+        }
+        catch (Exception) { }
+
+        return words;
+    }
+
+    public override bool ParseLine(string line, object? context = null)
+    {
+        letterGrid.Add(line);
+        return true;
+    }
+}