# 0929. Unique Email Addresses

https://leetcode.com/problems/unique-email-addresses

## Description

Every **valid email** consists of a **local name** and a **domain name**, separated by the `'@'` sign. Besides lowercase letters, the email may contain one or more `'.'` or `'+'`.

* For example, in `"alice@leetcode.com"`, `"alice"` is the **local name**, and `"leetcode.com"` is the **domain name**.

If you add periods `'.'` between some characters in the **local name** part of an email address, mail sent there will be forwarded to the same address without dots in the local name. Note that this rule **does not apply** to **domain names**.

* For example, `"alice.z@leetcode.com"` and `"alicez@leetcode.com"` forward to the same email address.

If you add a plus `'+'` in the **local name**, everything after the first plus sign **will be ignored**. This allows certain emails to be filtered. Note that this rule **does not apply** to **domain names**.

* For example, `"m.y+name@email.com"` will be forwarded to `"my@email.com"`.

It is possible to use both of these rules at the same time.

Given an array of strings `emails` where we send one email to each `email[i]`, return _the number of different addresses that actually receive mails_.

**Example 1:**

```
**Input:** emails = ["test.email+alex@leetcode.com","test.e.mail+bob.cathy@leetcode.com","testemail+david@lee.tcode.com"]
**Output:** 2
**Explanation:** "testemail@leetcode.com" and "testemail@lee.tcode.com" actually receive mails.
```

**Example 2:**

```
**Input:** emails = ["a@leetcode.com","b@leetcode.com","c@leetcode.com"]
**Output:** 3
```

**Constraints:**

* `1 <= emails.length <= 100`
* `1 <= emails[i].length <= 100`
* `email[i]` consist of lowercase English letters, `'+'`, `'.'` and `'@'`.
* Each `emails[i]` contains exactly one `'@'` character.
* All local and domain names are non-empty.
* Local names do not start with a `'+'` character.

## ac

```java
```
