[LeetCode] 49. Group Anagrams

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

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example 1:

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

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.

My Solution

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        anagrams = collections.defaultdict(list) # 1
        
        for word in strs:
            anagrams[''.join(sorted(word))].append(word) # 2
            
        return list(anagrams.values()) # 3

#1

• #2 append 에서 keyError를 방지하기 위해 defaultdict 사용.
• {'key': [value1,value2]} 형태로 만들기 위해 defaultdict(list) 선언.

#2

• ate eat tea는 정렬하면 aet가 됨.
• {'aet': ['ate', 'eat', 'tea']} 형태로 dictionary가 만들어짐

#3

• 최종 출력형태에 맞추기 위해 values()로 dict에서 list를 추출하여 list에 담아준다.