Bình luận

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  bengokyeuanh99  đã bình luận lúc 6, Tháng 9, 2025, 17:43

  Full AC

  include <iostream>

  include <string>

  include <unordered_set>

  using namespace std;

  bool isValidEmail(const string& email) { static const unordered_set<string> validDomains = { "@gmail.com", "@28tech.com.vn", "@yahoo.com", "@hotmail.com" };

  int atCount = 0;
  for (char c : email) {
      if (!(isalnum(c) || c == '@' || c == '.' || c == '_')) return false;
      if (c == '@') atCount++;
  }
  if (atCount != 1) return false;
  
  for (const auto& d : validDomains) {
      if (email.size() >= d.size() &&
          email.compare(email.size() - d.size(), d.size(), d) == 0) {
          return true;
      }
  }
  return false;
  

  }

  int main() { ios::syncwithstdio(false); cin.tie(nullptr);

  int t;
  cin >> t;
  string email;
  while (t--) {
      cin >> email;
      cout << (isValidEmail(email) ? "YES" : "NO") << '\n';
  }
  return 0;
  

  }