Refactor group_anagrams to use character frequency as key

Replaced sorted strings with character frequency tuples as keys for grouping anagrams. This improves algorithm efficiency by avoiding repeated sorting operations for each word. The behavior of the function remains unchanged.

Author: nicholasadamou

Arrays & Hashing/group_anagrams.py

@@ -9,15 +9,16 @@ def group_anagrams(words: List[str]) -> List[List[str]]:
     anagram_groups = defaultdict(list)
 
     for word in words:
-        sorted_word = "".join(sorted(word))
+        # Create a character frequency tuple
+        char_count = [0] * 26  # Assuming only lowercase letters
+        for char in word:
+            char_count[ord(char) - ord("a")] += 1
 
-        if sorted_word in anagram_groups:
-            anagram_groups[sorted_word].append(word)
-            continue
+        # Use the tuple of counts as the key
+        key = tuple(char_count)
+        anagram_groups[key].append(word)
 
-        anagram_groups[sorted_word].append(word)
-
-    return [group for group in anagram_groups.values()]
+    return list(anagram_groups.values())
 
 
 class Test(unittest.TestCase):