made it run parralell to speed it up and got rid of words bigger then 6 chars

Program.cs

@@ -7,8 +7,13 @@
         var wordSet = new HashSet<string>(words);
 
         // Find all combinations that form a 6-letter word
+        var filteredWords = words.Where(w => w.Length <= 6).ToList();
         var combos = new HashSet<string>();
-        FindCombinations(words, new List<string>(), 0, wordSet, combos);
+
+        Parallel.ForEach(filteredWords, word =>
+        {
+            FindCombinations(word, filteredWords, new List<string> { word }, word.Length, wordSet, combos);
+        });
 
         // Print out all found combinations
         foreach (var combo in combos)
@@ -17,20 +22,23 @@
         }
     }
 
-    static void FindCombinations(List<string> words, List<string> currentCombination, int currentLength, HashSet<string> wordSet, HashSet<string> combos)
+    static void FindCombinations(string currentWord, 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
+        // Check if the current combination forms a valid 6-letter word
         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
+                lock (combos) // Ensure thread-safe access to combos
+                {
+                    if (combos.Add(result)) // Add to the set and check for uniqueness
                     {
                         Console.WriteLine(result); // Echo out the found combination
                     }
                 }
+            }
             return;
         }
 
@@ -43,10 +51,15 @@
                 continue;
             }
 
+            // Avoid duplicate combinations
+            if (currentCombination.Contains(word))
+            {
+                continue;
+            }
+
             // Add the word to the current combination and recurse
-            currentCombination.Add(word);
+            var newCombination = new List<string>(currentCombination) { word };
-            FindCombinations(words, currentCombination, currentLength + word.Length, wordSet, combos);
+            FindCombinations(currentWord, words, newCombination, 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+d71eb795d7a7de915bd319b60249ee90f2bc5538")]
+[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0+4c9023445a69c66dd72633b718cbef8565efa4c6")]
 [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 @@
-68c131bf4bbdc8c6ee3c840269c62122d679fae9c2f5cb638dc03527d6749d88
+1a32798c3322f35ba2923c1415f22677216d6d303f9a0a3678dd3e3d2ec1deba