// generate_measurements.cpp
//
// Simple standalone generator for 1BRC-style data, no Java/Maven needed.
//
// Build:
//   g++ -O2 -o generate_measurements generate_measurements.cpp
//
// Run:
//   ./generate_measurements 1000000000 > measurements.txt
//   (defaults to 1,000,000,000 rows if no argument given)
//
// Output format matches the original challenge:
//   <station name>;<temperature to 1 decimal place>
//
// Uses the real 413 station names + mean temperatures from the official
// challenge's CreateMeasurements.java. Temperatures are generated as
// station_mean + gaussian noise, clamped to [-99.9, 99.9] — the same
// approach the official generator uses.
//
// Note: station names include UTF-8 characters (e.g. "Zürich", "Abéché"),
// so save/compile this file as UTF-8.

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <random>
#include <string>
#include <vector>

int main(int argc, char **argv) {
  long long numRows = 1'000'000'000LL;
  if (argc > 1) {
    numRows = std::atoll(argv[1]);
    if (numRows <= 0) {
      std::fprintf(stderr, "Invalid row count: %s\n", argv[1]);
      return 1;
    }
  }

  // Station name -> approximate mean annual temperature (Celsius).
  // A representative subset of real-world locations/climates.
  // Station name -> average temperature (Celsius), taken directly from
  // the official 1BRC repo's CreateMeasurements.java (413 real stations).
  static const std::vector<std::pair<const char *, double>> stations = {
      {"Abha", 18.0},
      {"Abidjan", 26.0},
      {"Abéché", 29.4},
      {"Accra", 26.4},
      {"Addis Ababa", 16.0},
      {"Adelaide", 17.3},
      {"Aden", 29.1},
      {"Ahvaz", 25.4},
      {"Albuquerque", 14.0},
      {"Alexandra", 11.0},
      {"Alexandria", 20.0},
      {"Algiers", 18.2},
      {"Alice Springs", 21.0},
      {"Almaty", 10.0},
      {"Amsterdam", 10.2},
      {"Anadyr", -6.9},
      {"Anchorage", 2.8},
      {"Andorra la Vella", 9.8},
      {"Ankara", 12.0},
      {"Antananarivo", 17.9},
      {"Antsiranana", 25.2},
      {"Arkhangelsk", 1.3},
      {"Ashgabat", 17.1},
      {"Asmara", 15.6},
      {"Assab", 30.5},
      {"Astana", 3.5},
      {"Athens", 19.2},
      {"Atlanta", 17.0},
      {"Auckland", 15.2},
      {"Austin", 20.7},
      {"Baghdad", 22.77},
      {"Baguio", 19.5},
      {"Baku", 15.1},
      {"Baltimore", 13.1},
      {"Bamako", 27.8},
      {"Bangkok", 28.6},
      {"Bangui", 26.0},
      {"Banjul", 26.0},
      {"Barcelona", 18.2},
      {"Bata", 25.1},
      {"Batumi", 14.0},
      {"Beijing", 12.9},
      {"Beirut", 20.9},
      {"Belgrade", 12.5},
      {"Belize City", 26.7},
      {"Benghazi", 19.9},
      {"Bergen", 7.7},
      {"Berlin", 10.3},
      {"Bilbao", 14.7},
      {"Birao", 26.5},
      {"Bishkek", 11.3},
      {"Bissau", 27.0},
      {"Blantyre", 22.2},
      {"Bloemfontein", 15.6},
      {"Boise", 11.4},
      {"Bordeaux", 14.2},
      {"Bosaso", 30.0},
      {"Boston", 10.9},
      {"Bouaké", 26.0},
      {"Bratislava", 10.5},
      {"Brazzaville", 25.0},
      {"Bridgetown", 27.0},
      {"Brisbane", 21.4},
      {"Brussels", 10.5},
      {"Bucharest", 10.8},
      {"Budapest", 11.3},
      {"Bujumbura", 23.8},
      {"Bulawayo", 18.9},
      {"Burnie", 13.1},
      {"Busan", 15.0},
      {"Cabo San Lucas", 23.9},
      {"Cairns", 25.0},
      {"Cairo", 21.4},
      {"Calgary", 4.4},
      {"Canberra", 13.1},
      {"Cape Town", 16.2},
      {"Changsha", 17.4},
      {"Charlotte", 16.1},
      {"Chiang Mai", 25.8},
      {"Chicago", 9.8},
      {"Chihuahua", 18.6},
      {"Chișinău", 10.2},
      {"Chittagong", 25.9},
      {"Chongqing", 18.6},
      {"Christchurch", 12.2},
      {"City of San Marino", 11.8},
      {"Colombo", 27.4},
      {"Columbus", 11.7},
      {"Conakry", 26.4},
      {"Copenhagen", 9.1},
      {"Cotonou", 27.2},
      {"Cracow", 9.3},
      {"Da Lat", 17.9},
      {"Da Nang", 25.8},
      {"Dakar", 24.0},
      {"Dallas", 19.0},
      {"Damascus", 17.0},
      {"Dampier", 26.4},
      {"Dar es Salaam", 25.8},
      {"Darwin", 27.6},
      {"Denpasar", 23.7},
      {"Denver", 10.4},
      {"Detroit", 10.0},
      {"Dhaka", 25.9},
      {"Dikson", -11.1},
      {"Dili", 26.6},
      {"Djibouti", 29.9},
      {"Dodoma", 22.7},
      {"Dolisie", 24.0},
      {"Douala", 26.7},
      {"Dubai", 26.9},
      {"Dublin", 9.8},
      {"Dunedin", 11.1},
      {"Durban", 20.6},
      {"Dushanbe", 14.7},
      {"Edinburgh", 9.3},
      {"Edmonton", 4.2},
      {"El Paso", 18.1},
      {"Entebbe", 21.0},
      {"Erbil", 19.5},
      {"Erzurum", 5.1},
      {"Fairbanks", -2.3},
      {"Fianarantsoa", 17.9},
      {"Flores,  Petén", 26.4},
      {"Frankfurt", 10.6},
      {"Fresno", 17.9},
      {"Fukuoka", 17.0},
      {"Gabès", 19.5},
      {"Gaborone", 21.0},
      {"Gagnoa", 26.0},
      {"Gangtok", 15.2},
      {"Garissa", 29.3},
      {"Garoua", 28.3},
      {"George Town", 27.9},
      {"Ghanzi", 21.4},
      {"Gjoa Haven", -14.4},
      {"Guadalajara", 20.9},
      {"Guangzhou", 22.4},
      {"Guatemala City", 20.4},
      {"Halifax", 7.5},
      {"Hamburg", 9.7},
      {"Hamilton", 13.8},
      {"Hanga Roa", 20.5},
      {"Hanoi", 23.6},
      {"Harare", 18.4},
      {"Harbin", 5.0},
      {"Hargeisa", 21.7},
      {"Hat Yai", 27.0},
      {"Havana", 25.2},
      {"Helsinki", 5.9},
      {"Heraklion", 18.9},
      {"Hiroshima", 16.3},
      {"Ho Chi Minh City", 27.4},
      {"Hobart", 12.7},
      {"Hong Kong", 23.3},
      {"Honiara", 26.5},
      {"Honolulu", 25.4},
      {"Houston", 20.8},
      {"Ifrane", 11.4},
      {"Indianapolis", 11.8},
      {"Iqaluit", -9.3},
      {"Irkutsk", 1.0},
      {"Istanbul", 13.9},
      {"İzmir", 17.9},
      {"Jacksonville", 20.3},
      {"Jakarta", 26.7},
      {"Jayapura", 27.0},
      {"Jerusalem", 18.3},
      {"Johannesburg", 15.5},
      {"Jos", 22.8},
      {"Juba", 27.8},
      {"Kabul", 12.1},
      {"Kampala", 20.0},
      {"Kandi", 27.7},
      {"Kankan", 26.5},
      {"Kano", 26.4},
      {"Kansas City", 12.5},
      {"Karachi", 26.0},
      {"Karonga", 24.4},
      {"Kathmandu", 18.3},
      {"Khartoum", 29.9},
      {"Kingston", 27.4},
      {"Kinshasa", 25.3},
      {"Kolkata", 26.7},
      {"Kuala Lumpur", 27.3},
      {"Kumasi", 26.0},
      {"Kunming", 15.7},
      {"Kuopio", 3.4},
      {"Kuwait City", 25.7},
      {"Kyiv", 8.4},
      {"Kyoto", 15.8},
      {"La Ceiba", 26.2},
      {"La Paz", 23.7},
      {"Lagos", 26.8},
      {"Lahore", 24.3},
      {"Lake Havasu City", 23.7},
      {"Lake Tekapo", 8.7},
      {"Las Palmas de Gran Canaria", 21.2},
      {"Las Vegas", 20.3},
      {"Launceston", 13.1},
      {"Lhasa", 7.6},
      {"Libreville", 25.9},
      {"Lisbon", 17.5},
      {"Livingstone", 21.8},
      {"Ljubljana", 10.9},
      {"Lodwar", 29.3},
      {"Lomé", 26.9},
      {"London", 11.3},
      {"Los Angeles", 18.6},
      {"Louisville", 13.9},
      {"Luanda", 25.8},
      {"Lubumbashi", 20.8},
      {"Lusaka", 19.9},
      {"Luxembourg City", 9.3},
      {"Lviv", 7.8},
      {"Lyon", 12.5},
      {"Madrid", 15.0},
      {"Mahajanga", 26.3},
      {"Makassar", 26.7},
      {"Makurdi", 26.0},
      {"Malabo", 26.3},
      {"Malé", 28.0},
      {"Managua", 27.3},
      {"Manama", 26.5},
      {"Mandalay", 28.0},
      {"Mango", 28.1},
      {"Manila", 28.4},
      {"Maputo", 22.8},
      {"Marrakesh", 19.6},
      {"Marseille", 15.8},
      {"Maun", 22.4},
      {"Medan", 26.5},
      {"Mek'ele", 22.7},
      {"Melbourne", 15.1},
      {"Memphis", 17.2},
      {"Mexicali", 23.1},
      {"Mexico City", 17.5},
      {"Miami", 24.9},
      {"Milan", 13.0},
      {"Milwaukee", 8.9},
      {"Minneapolis", 7.8},
      {"Minsk", 6.7},
      {"Mogadishu", 27.1},
      {"Mombasa", 26.3},
      {"Monaco", 16.4},
      {"Moncton", 6.1},
      {"Monterrey", 22.3},
      {"Montreal", 6.8},
      {"Moscow", 5.8},
      {"Mumbai", 27.1},
      {"Murmansk", 0.6},
      {"Muscat", 28.0},
      {"Mzuzu", 17.7},
      {"N'Djamena", 28.3},
      {"Naha", 23.1},
      {"Nairobi", 17.8},
      {"Nakhon Ratchasima", 27.3},
      {"Napier", 14.6},
      {"Napoli", 15.9},
      {"Nashville", 15.4},
      {"Nassau", 24.6},
      {"Ndola", 20.3},
      {"New Delhi", 25.0},
      {"New Orleans", 20.7},
      {"New York City", 12.9},
      {"Ngaoundéré", 22.0},
      {"Niamey", 29.3},
      {"Nicosia", 19.7},
      {"Niigata", 13.9},
      {"Nouadhibou", 21.3},
      {"Nouakchott", 25.7},
      {"Novosibirsk", 1.7},
      {"Nuuk", -1.4},
      {"Odesa", 10.7},
      {"Odienné", 26.0},
      {"Oklahoma City", 15.9},
      {"Omaha", 10.6},
      {"Oranjestad", 28.1},
      {"Oslo", 5.7},
      {"Ottawa", 6.6},
      {"Ouagadougou", 28.3},
      {"Ouahigouya", 28.6},
      {"Ouarzazate", 18.9},
      {"Oulu", 2.7},
      {"Palembang", 27.3},
      {"Palermo", 18.5},
      {"Palm Springs", 24.5},
      {"Palmerston North", 13.2},
      {"Panama City", 28.0},
      {"Parakou", 26.8},
      {"Paris", 12.3},
      {"Perth", 18.7},
      {"Petropavlovsk-Kamchatsky", 1.9},
      {"Philadelphia", 13.2},
      {"Phnom Penh", 28.3},
      {"Phoenix", 23.9},
      {"Pittsburgh", 10.8},
      {"Podgorica", 15.3},
      {"Pointe-Noire", 26.1},
      {"Pontianak", 27.7},
      {"Port Moresby", 26.9},
      {"Port Sudan", 28.4},
      {"Port Vila", 24.3},
      {"Port-Gentil", 26.0},
      {"Portland (OR)", 12.4},
      {"Porto", 15.7},
      {"Prague", 8.4},
      {"Praia", 24.4},
      {"Pretoria", 18.2},
      {"Pyongyang", 10.8},
      {"Rabat", 17.2},
      {"Rangpur", 24.4},
      {"Reggane", 28.3},
      {"Reykjavík", 4.3},
      {"Riga", 6.2},
      {"Riyadh", 26.0},
      {"Rome", 15.2},
      {"Roseau", 26.2},
      {"Rostov-on-Don", 9.9},
      {"Sacramento", 16.3},
      {"Saint Petersburg", 5.8},
      {"Saint-Pierre", 5.7},
      {"Salt Lake City", 11.6},
      {"San Antonio", 20.8},
      {"San Diego", 17.8},
      {"San Francisco", 14.6},
      {"San Jose", 16.4},
      {"San José", 22.6},
      {"San Juan", 27.2},
      {"San Salvador", 23.1},
      {"Sana'a", 20.0},
      {"Santo Domingo", 25.9},
      {"Sapporo", 8.9},
      {"Sarajevo", 10.1},
      {"Saskatoon", 3.3},
      {"Seattle", 11.3},
      {"Ségou", 28.0},
      {"Seoul", 12.5},
      {"Seville", 19.2},
      {"Shanghai", 16.7},
      {"Singapore", 27.0},
      {"Skopje", 12.4},
      {"Sochi", 14.2},
      {"Sofia", 10.6},
      {"Sokoto", 28.0},
      {"Split", 16.1},
      {"St. John's", 5.0},
      {"St. Louis", 13.9},
      {"Stockholm", 6.6},
      {"Surabaya", 27.1},
      {"Suva", 25.6},
      {"Suwałki", 7.2},
      {"Sydney", 17.7},
      {"Tabora", 23.0},
      {"Tabriz", 12.6},
      {"Taipei", 23.0},
      {"Tallinn", 6.4},
      {"Tamale", 27.9},
      {"Tamanrasset", 21.7},
      {"Tampa", 22.9},
      {"Tashkent", 14.8},
      {"Tauranga", 14.8},
      {"Tbilisi", 12.9},
      {"Tegucigalpa", 21.7},
      {"Tehran", 17.0},
      {"Tel Aviv", 20.0},
      {"Thessaloniki", 16.0},
      {"Thiès", 24.0},
      {"Tijuana", 17.8},
      {"Timbuktu", 28.0},
      {"Tirana", 15.2},
      {"Toamasina", 23.4},
      {"Tokyo", 15.4},
      {"Toliara", 24.1},
      {"Toluca", 12.4},
      {"Toronto", 9.4},
      {"Tripoli", 20.0},
      {"Tromsø", 2.9},
      {"Tucson", 20.9},
      {"Tunis", 18.4},
      {"Ulaanbaatar", -0.4},
      {"Upington", 20.4},
      {"Ürümqi", 7.4},
      {"Vaduz", 10.1},
      {"Valencia", 18.3},
      {"Valletta", 18.8},
      {"Vancouver", 10.4},
      {"Veracruz", 25.4},
      {"Vienna", 10.4},
      {"Vientiane", 25.9},
      {"Villahermosa", 27.1},
      {"Vilnius", 6.0},
      {"Virginia Beach", 15.8},
      {"Vladivostok", 4.9},
      {"Warsaw", 8.5},
      {"Washington, D.C.", 14.6},
      {"Wau", 27.8},
      {"Wellington", 12.9},
      {"Whitehorse", -0.1},
      {"Wichita", 13.9},
      {"Willemstad", 28.0},
      {"Winnipeg", 3.0},
      {"Wrocław", 9.6},
      {"Xi'an", 14.1},
      {"Yakutsk", -8.8},
      {"Yangon", 27.5},
      {"Yaoundé", 23.8},
      {"Yellowknife", -4.3},
      {"Yerevan", 12.4},
      {"Yinchuan", 9.0},
      {"Zagreb", 10.7},
      {"Zanzibar City", 26.0},
      {"Zürich", 9.3}};

  std::mt19937 rng(std::random_device{}());
  std::uniform_int_distribution<size_t> stationPicker(0, stations.size() - 1);

  // Use a big stdio buffer + manual formatting for speed, since default
  // cout/printf per-line for a billion rows would otherwise dominate runtime.
  constexpr size_t BUF_SIZE = 1 << 20; // 1 MB
  std::vector<char> buffer(BUF_SIZE);
  size_t bufPos = 0;

  auto flushBuffer = [&]() {
    std::fwrite(buffer.data(), 1, bufPos, stdout);
    bufPos = 0;
  };

  auto writeStr = [&](const char *s, size_t len) {
    if (bufPos + len > BUF_SIZE)
      flushBuffer();
    std::memcpy(buffer.data() + bufPos, s, len);
    bufPos += len;
  };

  for (long long i = 0; i < numRows; ++i) {
    size_t idx = stationPicker(rng);
    const char *name = stations[idx].first;
    double mean = stations[idx].second;

    std::normal_distribution<double> tempDist(mean, 8.0);
    double temp = tempDist(rng);
    if (temp > 99.9)
      temp = 99.9;
    if (temp < -99.9)
      temp = -99.9;

    char line[160]; // headroom for longer UTF-8 station names
    int len = std::snprintf(line, sizeof(line), "%s;%.1f\n", name, temp);
    writeStr(line, static_cast<size_t>(len));
  }

  flushBuffer();
  return 0;
}