## Merge Accounts by Shared Email Each account record begins with a person's name followed by one or more email addresses. Two records belong to the same person if they share at least one email address, directly or through a chain of shared addresses. Merge all records that refer to the same person. ### Function Signature ```python def merge_accounts(accounts: list[list[str]]) -> list[list[str]]: ... ``` ### Input - Each record has the form `[name, email_1, email_2, ...]`. - Every email address belongs to exactly one real person. - Records for the same real person use the same name. ### Output Return one record per person. Each output record must contain the person's name followed by all of their distinct email addresses in lexicographic order. The order of person records does not matter. ### Constraints - `1 <= len(accounts) <= 10_000` - Each account contains at least one email address. - The total number of email occurrences is at most `200_000`. ### Example ```text Input: [ ["John", "johnsmith@mail.com", "john_newyork@mail.com"], ["John", "johnsmith@mail.com", "john00@mail.com"], ["Mary", "mary@mail.com"], ["John", "johnnybravo@mail.com"] ] One valid output: [ ["John", "john00@mail.com", "john_newyork@mail.com", "johnsmith@mail.com"], ["Mary", "mary@mail.com"], ["John", "johnnybravo@mail.com"] ] ``` ### Clarifications - Sharing is transitive: if record A shares an email with B and B shares another email with C, all three records merge. - Duplicate occurrences of the same email must appear only once in the merged record.