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

Program.cs

@@ -1,24 +1,65 @@
-class Program {
+class Program
-    static void Main() {
+{
-        // get all the words form the text file and put them into a hasset
+    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
+        // Find all combinations that form a 6-letter word
-        var seenCombinations = new HashSet<string>();
+        var filteredWords = words.Where(w => w.Length <= 6).ToList();
-        var combos = words.SelectMany(
+        var combos = new HashSet<string>();
-                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();
 
-        // echo out all found words
+        Parallel.ForEach(filteredWords, word =>
-        combos.ForEach(Console.WriteLine);
+        {
+            FindCombinations(word, filteredWords, new List<string> { word }, word.Length, wordSet, combos);
+        });
 
+        // Print out all found combinations
+        foreach (var combo in combos)
+        {
+            Console.WriteLine(combo);
+        }
+    }
+
+    static void FindCombinations(string currentWord, List<string> words, List<string> currentCombination, int currentLength, HashSet<string> wordSet, HashSet<string> combos)
+    {
+        // 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}";
+                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;
+        }
+
+        // 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;
+            }
+
+            // Avoid duplicate combinations
+            if (currentCombination.Contains(word))
+            {
+                continue;
+            }
+
+            // Add the word to the current combination and recurse
+            var newCombination = new List<string>(currentCombination) { word };
+            FindCombinations(currentWord, words, newCombination, currentLength + word.Length, wordSet, combos);
+        }
     }
 }

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+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 @@
-38d39cd6b0bba17b8e33dc8144efa9e3646f6745189f6a226aa41ca2ccf216ba
+1a32798c3322f35ba2923c1415f22677216d6d303f9a0a3678dd3e3d2ec1deba