Count Delivery Addresses after Local-Name Dot and Plus Rules

### Problem For this task's email-address rules, split each string at its single `@`. In the local part only, discard every dot and ignore the first plus sign and everything following it. Leave the domain unchanged. Return the number of distinct resulting delivery addresses. These rules describe the supplied problem model, not a claim about all email providers. ```cpp class Solution { public: int numUniqueEmails(vector<string>& emails); }; ``` ### Examples **Example 1:** ```text Input: emails = ["a.b+tag@sample.com","ab@sample.com","ab@sa.mple.com"] Output: 2 Explanation: The first two normalize to ab@sample.com. The domain dot in sa.mple.com remains significant. ``` **Example 2:** ```text Input: emails = ["x+u@a.com","x+v@a.com","x@b.com"] Output: 2 Explanation: Both a.com addresses deliver to x@a.com; x@b.com remains separate. ``` ### Constraints - `1 <= emails.length <= 100`. - `1 <= emails[i].length <= 100`. - Characters are lowercase English letters, `+`, `.`, and `@`. - Each address has exactly one `@`; local and domain names are nonempty. - Local names do not start with `+`. - Domains end with `.com` and contain at least one character before that suffix. ### Contract considerations Only lowercase letters, plus,dot and @ occur. Domain names end in .com and have at least one character before that suffix. ```hint Read the boundary condition The at-sign separates two regions with different transformation rules. ``` ### Boundary reminders Only lowercase letters, plus,dot and @ occur. Domain names end in .com and have at least one character before that suffix.