Group Anagrams

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Example 1:

Input: strs = ["eat","tea","tan","ate","nat","bat"]

Output: [["bat"],["nat","tan"],["ate","eat","tea"]]

Explanation:

• There is no string in strs that can be rearranged to form "bat".
• The strings "nat" and "tan" are anagrams as they can be rearranged to form each other.
• The strings "ate", "eat", and "tea" are anagrams as they can be rearranged to form each other.

Example 2:

Input: strs = [""]

Output: [[""]]

Example 3:

Input: strs = ["a"]

Output: [["a"]]

Constraints:

• 1 <= strs.length <= 10<sup>4</sup>
• 0 <= strs[i].length <= 100
• strs[i] consists of lowercase English letters.

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        sorted_strs = defaultdict(list)  # sorted: original
        anagram_map = {}
        res = []

        for s in strs:
            sorted_strs[s] = "".join(sorted(s))

        for original, sorted_val in sorted_strs.items():
            if sorted_val in anagram_map:
                anagram_map[sorted_val].append(original)
            else:
                anagram_map[sorted_val] = [original]

        for value in anagram_map.values():
            res.append(value)

        return res