add group-anagrams

0049_group-anagrams/python3/naive.py

@@ -0,0 +1,13 @@
+# Time: O(N * MlogM) where N is len(strs) and M is num of chars in a string
+# Space: O(N)
+
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        groups = {}
+        
+        for s in strs:
+            s_sorted = ''.join(sorted(s))
+            
+            groups[s_sorted] = groups.get(s_sorted, []) + [s]
+        
+        return list(groups.values())

0049_group-anagrams/python3/solution.py

@@ -0,0 +1,24 @@
+# Time: O(N · M)
+# Space: O(N)
+
+from collections import Counter, defaultdict
+
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        # If key doesn't exist, creates empty list using `list`
+        # factory/ctor function
+        groups = defaultdict(list)
+        
+        for s in strs:
+            # Keep counter for num of times each letter appeared
+            counts = [0] * 26
+            
+            for c in s:
+                i = ord(c) - ord('a')
+                counts[i] += 1
+            
+            # Lists aren't hashable, so we need to convert the counts
+            # to tuple so that we can key them
+            groups[tuple(counts)].append(s)
+        
+        return list(groups.values())