49. Group Anagrams

Problem Link

Description

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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 <= 104
• 0 <= strs[i].length <= 100
• strs[i] consists of lowercase English letters.

Solution

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Python3

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        res = defaultdict(list)
 
        def hash(s):
            counter = [0] * 26
 
            for x in s:
                counter[ord(x) - ord('a')] += 1
            
            return ",".join(map(str, counter))
 
        for s in strs:
            res[hash(s)].append(s)
        
        return list(res.values())