929. Unique Email Addresses
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.
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, "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
Note:
1 <= emails[i].length <= 1001 <= emails.length <= 100- Each
emails[i]contains exactly one'@'character. - All local and domain names are non-empty.
- Local names do not start with a
'+'character.
題意：每封電子郵件都由一個(gè)本地名稱和一個(gè)域名組成，以 @ 符號(hào)分隔。里面可能包含‘+’和‘.’ 第一個(gè)‘+’后面的內(nèi)容會(huì)被忽略‘.’ 不影響蓉坎，求一共有多少電子郵件
思路：按照題目要求飞袋，過濾扣泊，最后用set去重搞糕，輸出個(gè)數(shù)脊髓。
class Solution {
public:
int numUniqueEmails(vector<string>& emails) {
unordered_set<string> hash;
for(auto email:emails)
{
int at=email.find('@');
string name;
for(auto c:email.substr(0,at))
if(c=='+')
break;
else if(c!='.')
name+=c;
string domain=email.substr(at+1);
hash.insert(name+'@'+domain);
}
return hash.size();
}
};
