✅ [Python] split then replace (with detailed comments)
\u2705 IF YOU LIKE THIS SOLUTION, PLEASE UPVOTE.\n*\nThis solution employs trivial string operations. Time complexity is linear: *O(N). Space complexity is line
**\u2705 IF YOU LIKE THIS SOLUTION, PLEASE UPVOTE.**\n****\nThis solution employs trivial string operations. Time complexity is linear: **O(N)**. Space complexity is linear: **O(N)**.\n\n```\nclass Solution:\n    def numUniqueEmails(self, emails: List[str]) -> int:\n        unique = set()\n        for e in emails:\n            loc, dom = e.split("@")                                 # get parts of email\n            fwd = loc.split("+")[0].replace(".", "") + "@" + dom    # build forward email\n            unique.add(fwd)\n        return len(unique)\n```
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