Time: 22 ms (21.01%), Space: 22.7 MB (24.41%) - LeetHub

0049-group-anagrams/0049-group-anagrams.py

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+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        """
+        Complexities
+        Time:  O(Mn)
+        Space: O(n)
+        
+        where n = len(strs)
+              M = max(len(str[i])
+        """
+
+
+        # Store strs in dictionary, keyed by sorted string (or frequency count)
+        strsByAnagram = dict({})
+
+        # Conversion helper - O(M)
+        def toFreqTuple(s: str):
+            freq = [0] * 26
+            for l in s:
+                letter_index = ord(l) - ord('a')
+                freq[letter_index] += 1
+            return tuple(freq) 
+
+
+        # Map each s in str to its key - O(Mn)
+        for s in strs:
+            key = toFreqTuple(s)
+            strsByAnagram[key] = [*strsByAnagram.get(key, []), s]
+
+        # Convert dict to array to return - O(n)
+        return list(strsByAnagram.values())