Medium — Hash Table | String | Sorting

The Problem

Group anagrams together from an array of strings, where anagrams are words that contain the same characters in different orders.

Approach

Use a hash map where the key is the sorted version of each word and the value is a list of all words that have the same sorted form. Words with identical sorted characters are anagrams and get grouped together.

Time: O(n * k log k) · Space: O(n * k)

Code

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        anagrams_map = {}

        for word in strs:
            sorted_word = "".join(sorted(word))
            if sorted_word in anagrams_map:
                anagrams_map[sorted_word].append(word)
            else:
                anagrams_map[sorted_word] = [word]

        return list(anagrams_map.values())

Watch It Run

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