Run: 2026-04-24-01KQ036YC8J7ZE7STADT5JGJ47

To solve this problem, we need to extract all valid email addresses from a given text. The valid email addresses are those that conform to the standard email format, which includes a local part followed by '@' and a domain part. The domain part must end with a top-level domain (TLD) consisting of at least two letters. Invalid email addresses, as marked in the text, should be excluded. ### Approach 1. **Regular Expression for Valid Emails**: We use a regular expression to match valid email addresses. The pattern is designed to ensure: - The local part (before '@') consists of word characters (letters, digits, underscores), dots, or hyphens. - The domain part (after '@') consists of one or more subdomains followed by a dot and a TLD. Each subdomain can include word characters, dots, or hyphens. The TLD must be at least two letters long. 2. **Processing the Text**: The text is scanned using the regular expression to find all matches, which correspond to valid email addresses. 3. **Output**: The extracted email addresses are joined into a comma-separated string without any spaces. ### Solution Code ```python import re text = """Contact information: 1. John Doe - john.doe@example.com 2. Jane Smith - jane@smith-family.net 3. support@company.co.uk 4. info@subdomain.example.org 5. Invalid email: not.an.email.com 6. Another invalid: @missing-username.com""" pattern = r'[\w\.-]+@([\w\.-]+\.)+[a-zA-Z]{2,}' emails = re.findall(pattern, text) result = ','.join(emails) print(result) ``` ### Explanation 1. **Regular Expression Pattern**: The pattern `[\w\.-]+@([\w\.-]+\.)+[a-zA-Z]{2,}` breaks down as follows: - `[\w\.-]+`: Matches the local part of the email, allowing word characters, dots, and hyphens. - `@`: Matches the '@' symbol literally. - `([\w\.-]+\.)+`: Matches one or more subdomains, each consisting of word characters, dots, or hyphens followed by a dot. - `[a-zA-Z]{2,}`: Matches the TLD, which must be at least two letters long. 2. **Finding Matches**: The `re.findall` function scans the text for all occurrences that match the pattern, returning a list of valid email addresses. 3. **Result Construction**: The list of email addresses is joined into a single string separated by commas, with no spaces between them. This results in the output: `john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org`. This approach efficiently extracts valid email addresses while excluding invalid ones as specified, leveraging regular expressions for precise pattern matching.