题目要求
Every email consists of a local name and a domain name, separated by the @ sign.
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. For example, "alice.z@leetcode.com" and "alicez@leetcode.com" forward to the same email address. (Note that this rule does not apply for domain names.)
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 m.y+name@email.com will be forwarded to my@email.com. (Again, this rule does not apply for domain names.)
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?
Input: ["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
1 <= emails[i].length <= 1001 <= emails.length <= 100
Each emails[i]contains exactly one '@' character.
题目分析及思路
题目要求得到一组邮件地址中不重复的地址的个数，规则是用户名部分有‘.’，则和无‘.’的用户名一样；用户名部分有‘+’，则忽略第一个‘+’后面的部分。两个规则可以同时生效，但对域名部分不起作用。所以先对邮件进行拆分，分为用户名部分和域名部分；之后先找到‘+’，去掉‘+’及后面部分，再去掉‘.’。最后再和‘@’及域名连接。因为要去重，所以使用一个set保存所有不重复的结果。
python代码
class Solution:
def numUniqueEmails(self, emails):
"""
:type emails: List[str]
:rtype: int
"""
emailsset = set()
for e in emails:
local,domain = e.split("@")
local = local.split("+")[0].replace(".","")
emailsset.add(local+"@"+domain)
return len(emailsset)