[Python] short solution, explained
What we need to do in this problem is carefully check cases and use functionality of strings in python.\n1. First, split each mail, using @ symbol.\n2. Then, re
What we need to do in this problem is carefully check cases and use functionality of strings in python.\n1. First, split each `mail`, using `@` symbol.\n2. Then, remove all `.` in local part of mail.\n3. If we found `+` in string, remove all symbols after this symbol.\n4. Finally, update `d[local + "@" + domain]`, increasing it by one.\n5. In the end calculate number of unique clean emails.\n\n#### Complexity\nIt is `O(m)` for time, where `m` is total length of all `emails`, space is potentially `O(m)` as well.\n\n#### Code\n```python\nclass Solution:\n    def numUniqueEmails(self, emails):\n        d = Counter()\n        for mail in emails:\n            local, domain = mail.split("@")\n            local = local.replace(".", "")\n            if "+" in local: local = local[:local.index("+")]\n            d[local + "@" + domain] += 1\n            \n        return len(d)\n```\n\nIf you have any questoins, feel free to ask. If you like the solution and explanation, please **upvote!**
['String']