Find Users With Valid E-Mails

Table: Users

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| user_id       | int     |
| name          | varchar |
| mail          | varchar |
+---------------+---------+
user_id is the primary key (column with unique values) for this table.
This table contains information of the users signed up in a website. Some e-mails are invalid.

Write a solution to find the users who have valid emails.

A valid e-mail has a prefix name and a domain where:

The prefix name is a string that may contain letters (upper or lower case), digits, underscore '_', period '.', and/or dash '-'. The prefix name must start with a letter.
The domain is '@leetcode.com'.
Return the result table in any order.

The result format is in the following example.

Example 1:

Input: 
Users table:
+---------+-----------+-------------------------+
| user_id | name      | mail                    |
+---------+-----------+-------------------------+
| 1       | Winston   | winston@leetcode.com    |
| 2       | Jonathan  | jonathanisgreat         |
| 3       | Annabelle | bella-@leetcode.com     |
| 4       | Sally     | sally.come@leetcode.com |
| 5       | Marwan    | quarz#2020@leetcode.com |
| 6       | David     | david69@gmail.com       |
| 7       | Shapiro   | .shapo@leetcode.com     |
+---------+-----------+-------------------------+
Output: 
+---------+-----------+-------------------------+
| user_id | name      | mail                    |
+---------+-----------+-------------------------+
| 1       | Winston   | winston@leetcode.com    |
| 3       | Annabelle | bella-@leetcode.com     |
| 4       | Sally     | sally.come@leetcode.com |
+---------+-----------+-------------------------+
Explanation: 
The mail of user 2 does not have a domain.
The mail of user 5 has the # sign which is not allowed.
The mail of user 6 does not have the leetcode domain.
The mail of user 7 starts with a period.

Solution

import pandas as pd


def valid_emails(users: pd.DataFrame) -> pd.DataFrame:
    return users[users['mail'].str.match('[A-Za-z][A-Za-z0-9_\.\-]*@leetcode(\?com)?\.com')]


if __name__ == '__main__':
    data = [[1, 'Winston', 'winston@leetcode.com'], [2, 'Jonathan', 'jonathanisgreat'],
            [3, 'Annabelle', 'bella-@leetcode.com'], [4, 'Sally', 'sally.come@leetcode.com'],
            [5, 'Marwan', 'quarz#2020@leetcode.com'], [6, 'David', 'david69@gmail.com'],
            [7, 'Shapiro', '.shapo@leetcode.com']]
    users = pd.DataFrame(data, columns=['user_id', 'name', 'mail']).astype(
        {'user_id': 'int64', 'name': 'object', 'mail': 'object'})
    print(valid_emails(users))