"""
49. Group Anagrams
Difficulty: Medium
https://leetcode.com/problems/group-anagrams/

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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 <= 10^4

        • 0 <= strs[i].length <= 100

        • strs[i] consists of lowercase English letters.
"""

from collections import defaultdict


class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        if not strs:
            return strs
        res = defaultdict(list)
        for s in strs:
            count = [0] * 26
            for c in s:
                count[ord(c) - ord("a")] += 1
            res[tuple(count)].append(s)

        return res.values()