Add 2_1_fix

Author: colorbox

929/step2_1_fix.cpp

@@ -0,0 +1,24 @@
+/*
+
+*/
+class Solution {
+ public:
+  int numUniqueEmails(vector<string>& emails) {
+    for (auto& email : emails) {
+      canonicalize_email(email);
+    }
+    set<string> unique_emails(emails.begin(), emails.end());
+    return unique_emails.size();
+  }
+
+ private:
+  void canonicalize_email(string& email) {
+    auto at_pos = email.rfind('@');
+    string local_part = email.substr(0, at_pos);
+    auto plus_pos = local_part.find('+');
+    string canonicalized_local_part = local_part.substr(0, plus_pos);
+    std::erase(canonicalized_local_part, '.');
+    string domain_part = email.substr(at_pos, email.size() - at_pos);
+    email = canonicalized_local_part + domain_part;
+  }
+};