Every email consists of a local name and a domain name, separated by the @ sign.

For example, in [email protected], alice is the local name, and leetcode.com is the domain name.

Besides lowercase letters, these emails may contain ‘.‘s or ‘+‘s.

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. For example, "[email protected]"

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, for example [email protected] will be forwarded to [email protected]

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

Given a list of emails, we send one email to each address in the list. How many different addresses actually receive mails?

Example 1:

Input: ["[email protected]","[email protected]","[email protected]"]
Output: 2
Explanation: "[email protected]" and "[email protected]" actually receive mails
 

Note:

• 1 <= emails[i].length <= 100
• 1 <= emails.length <= 100
• Each emails[i] contains exactly one ‘@‘ character.

每封電子郵件都由一個本地名稱和一個域名組成，以 @ 符號分隔。

例如，在 [email protected]中， alice 是本地名稱，而 leetcode.com 是域名。

除了小寫字母，這些電子郵件還可能包含 ‘,‘ 或 ‘+‘。

如果在電子郵件地址的本地名稱部分中的某些字符之間添加句點（‘.‘），則發往那裏的郵件將會轉發到本地名稱中沒有點的同一地址。例如，"[email protected]” 和 “[email protected]” 會轉發到同一電子郵件地址。 （請註意，此規則不適用於域名。）

如果在本地名稱中添加加號（‘+‘），則會忽略第一個加號後面的所有內容。這允許過濾某些電子郵件，例如 [email protected] 將轉發到 [email protected]。 （同樣，此規則不適用於域名。）

可以同時使用這兩個規則。

給定電子郵件列表 emails，我們會向列表中的每個地址發送一封電子郵件。實際收到郵件的不同地址有多少？

示例：

輸入：["[email protected]","[email protected]","[email protected]"]
輸出：2
解釋：實際收到郵件的是 "[email protected]" 和 "[email protected]"。

提示：

• 1 <= emails[i].length <= 100
• 1 <= emails.length <= 100
• 每封 emails[i] 都包含有且僅有一個 ‘@‘ 字符。

412ms

 1 class Solution {
 2     func numUniqueEmails(_ emails: [String]) -> Int {
 3         var es:Set<String> = Set<String>()
 4         for e in emails
 5         {
 6             //分割字符串
 7             var s: Array = e.components(separatedBy: "@")
 8             var str:String = String(s[0])
 9             //字符串替換
10             str = str.replacingOccurrences(of: ".", with: "")
11             //字符查找，返回字符索引
12             var ind = str.firstIndex(of: "+") ?? s[0].endIndex
13             if ind != str.endIndex
14             {
15                 //截取子字符串
16                 str = String(str[..<ind])
17             }
18             //拼接字符串,Set添加用.insert
19             es.insert(str + "@" + s[1])
20         }
21         return es.count
22     }
23 }

[Swift Weekly Contest 108]LeetCode929. 獨特的電子郵件地址 | Unique Email Addresses