Problem: 929. Unique Email Addresses 独特的电子邮件地址依次检查是否存在若存在分割字符串后缀检查长度4且最后存在.com前缀去掉和后续去掉’.检查前缀长度0Codeclass Solution { public: int numUniqueEmails(vectorstring emails) { unordered_setstring te; int a, n2; string pre, after, tmp; for(string s : emails) { a s.find(); if(a string::npos) { continue; } pre s.substr(0, a); after s.substr(a 1); n2 after.size(); if(n2 4) continue; if(after[n2-1]!m || after[n2-2]!o||after[n2-3]!c|| after[n2-4]!.) { continue; } a pre.find(); if(a!string::npos) { pre pre.substr(0, a); } tmp.clear(); for(char c : pre) { if(c!.) { tmp c; } } if(tmp.size() 0) continue; te.insert(tmp after); } return (int)te.size(); } };