[Leetcode]819. Most Common Word

📄 Description

Given a string paragraph and a string array of the banned words banned , return the most frequent word that is not banned. It is guaranteed there is at least one word that is not banned, and that the answer is unique.
The words in paragraph are case-insensitive and the answer should be returned in lowercase.

Example 1:

Input: paragraph = "Bob hit a ball, the hit BALL flew far after it was hit.", banned = ["hit"]
Output: "ball"
Explanation: 
"hit" occurs 3 times, but it is a banned word.
"ball" occurs twice (and no other word does), so it is the most frequent non-banned word in the paragraph. 
Note that words in the paragraph are not case sensitive,
that punctuation is ignored (even if adjacent to words, such as "ball,"), 
and that "hit" isn't the answer even though it occurs more because it is banned.

Example 2:

Input: paragraph = "a.", banned = []
Output: "a"

Constraints:

1 <= paragraph.length <= 1000

paragraph consists of English letters, space ' ' , or one of the symbols: "!?',;." .

0 <= banned.length <= 100

1 <= banned[i].length <= 10

banned[i] consists of only lowercase English letters.

💻 My submission

class Solution:
    def mostCommonWord(self, paragraph: str, banned: List[str]) -> str:
        
        words=[x for x in re.sub('[^\w]', ' ', paragraph).lower().split() if x not in banned]
        
        counter=Counter(words)
        
        return counter.most_common(1)[0][0]

🔨 How to solve the problm

1.正規表現による入力値の前処理

単語以外のすべての文字をスペースに変換します.

2.Counterオブジェクトを利用してmost common(1)で回答する

References

https://leetcode.com/problems/most-common-word/

Pythonアルゴリズムインタビュー(95種類のアルゴリズム問題で完成した符号化テスト)、朴相吉知音