Accounts Merge

You are given a list of accounts where each account is a list of strings: the first element is the name, and the rest are emails associated with that account. Two accounts belong to the same person if they share at least one common email. Merge the accounts of the same person, and for each merged account, return it in the format: [name, sorted emails...]. When merging, keep the name from the earliest account in the input list that contributed to the merged group. The final output must preserve the order of first appearance: a merged account's position is determined by the position of the first account (in the original list) that belongs to it. If two merged groups have the same first-account index, order them by that index. Emails in each output account must be sorted lexicographically. You must implement the function `merge_accounts(accounts)` that takes a list of lists of strings and returns a list of lists of strings. Note: The input contains no duplicate emails within the same account. Both the input and the output are in-memory lists; no file or network I/O is needed.

>>> merge_accounts([["John", "johnsmith@mail.com", "john00@mail.com"], ["John", "johnnybravo@mail.com"], ["John", "johnsmith@mail.com", "john_newyork@mail.com"], ["Mary", "mary@mail.com"]])
[['John', 'john00@mail.com', 'john_newyork@mail.com', 'johnsmith@mail.com'], ['John', 'johnnybravo@mail.com'], ['Mary', 'mary@mail.com']]