algo for checking more then 2 cobos -> SLOW

Program.cs

@@ -1,24 +1,52 @@
-class Program {
-    static void Main() {
-        // get all the words form the text file and put them into a hasset
+class Program
+{
+    static void Main()
+    {
+        // Read all words from the input.txt file and store them in a hash set for quick lookup
         var words = new List<string>(File.ReadAllLines("input.txt"));
         var wordSet = new HashSet<string>(words);
 
-        // Find all combos that forn a 6 letter word and make sure we dont have duplicates
-        var seenCombinations = new HashSet<string>();
-        var combos = words.SelectMany(
-                word1 => words.Where(word2 => word1 != word2),
-                (word1, word2) => new { word1, word2, combinedWord = word1 + word2 }
-        ).Where(
-            x => x.combinedWord.Length == 6 && wordSet.Contains(x.combinedWord)
-        ).Where(
-            x => seenCombinations.Add($"{x.word1}+{x.word2}")
-        ).Select(
-            x => $"{x.word1}+{x.word2}={x.combinedWord}"
-        ).ToList();
+        // Find all combinations that form a 6-letter word
+        var combos = new HashSet<string>();
+        FindCombinations(words, new List<string>(), 0, wordSet, combos);
 
-        // echo out all found words
-        combos.ForEach(Console.WriteLine);
+        // Print out all found combinations
+        foreach (var combo in combos)
+        {
+            Console.WriteLine(combo);
+        }
+    }
 
+    static void FindCombinations(List<string> words, List<string> currentCombination, int currentLength, HashSet<string> wordSet, HashSet<string> combos)
+    {
+        // If the current combination forms a 6-letter word, add it to the result list
+        if (currentLength == 6)
+        {
+            string combinedWord = string.Join("", currentCombination);
+            if (wordSet.Contains(combinedWord))
+            {
+                string result = $"{string.Join("+", currentCombination)}={combinedWord}";
+                if (combos.Add(result)) // Adds to the set and checks for uniqueness
+                {
+                    Console.WriteLine(result); // Echo out the found combination
+                }
+            }
+            return;
+        }
+
+        // Try adding each word to the current combination
+        foreach (var word in words)
+        {
+            // Skip if adding the word would exceed 6 characters
+            if (currentLength + word.Length > 6)
+            {
+                continue;
+            }
+
+            // Add the word to the current combination and recurse
+            currentCombination.Add(word);
+            FindCombinations(words, currentCombination, currentLength + word.Length, wordSet, combos);
+            currentCombination.RemoveAt(currentCombination.Count - 1); // Backtrack
+        }
     }
 }

obj/Debug/net8.0/6letterwordexercise.AssemblyInfo.cs

@@ -13,7 +13,7 @@ using System.Reflection;
 [assembly: System.Reflection.AssemblyCompanyAttribute("6letterwordexercise")]
 [assembly: System.Reflection.AssemblyConfigurationAttribute("Debug")]
 [assembly: System.Reflection.AssemblyFileVersionAttribute("1.0.0.0")]
-[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0+7a30bacb68910559e2c2bc33337d57c1364a1b60")]
+[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0+d71eb795d7a7de915bd319b60249ee90f2bc5538")]
 [assembly: System.Reflection.AssemblyProductAttribute("6letterwordexercise")]
 [assembly: System.Reflection.AssemblyTitleAttribute("6letterwordexercise")]
 [assembly: System.Reflection.AssemblyVersionAttribute("1.0.0.0")]

obj/Debug/net8.0/6letterwordexercise.AssemblyInfoInputs.cache

@@ -1 +1 @@
-38d39cd6b0bba17b8e33dc8144efa9e3646f6745189f6a226aa41ca2ccf216ba
+68c131bf4bbdc8c6ee3c840269c62122d679fae9c2f5cb638dc03527d6749d88