==============================
Smart Home Automation (Dart)
==============================

import 'dart:io';

void main() {
  SmartHome home = SmartHome();
  home.start();
}

class SmartHome {
  bool lightsOn = false;
  int temperature = 20;
  bool securityArmed = false;

  static const int minTemp = 15;
  static const int maxTemp = 30;

  void start() {
    while (true) {
      print('\n--- Smart Home Menu ---');
      print('1. Toggle Lights');
      print('2. Set Thermostat');
      print('3. Arm/Disarm Security');
      print('4. View Status');
      print('5. Exit');
      stdout.write('Choose an option: ');
      String? choice = stdin.readLineSync();

      switch (choice) {
        case '1':
          lightsOn = !lightsOn;
          print('Lights are now \${lightsOn ? "ON" : "OFF"}');
          break;

        case '2':
          setTemperature();
          break;

        case '3':
          securityArmed = !securityArmed;
          print('Security system is now \${securityArmed ? "ARMED" : "DISARMED"}');
          break;

        case '4':
          showStatus();
          break;

        case '5':
          print('Exiting... Goodbye!');
          return;

        default:
          print('Invalid choice!');
      }
    }
  }

  void setTemperature() {
    stdout.write('Enter temperature (15–30): ');
    int? temp = int.tryParse(stdin.readLineSync() ?? '');
    if (temp != null && temp >= minTemp && temp <= maxTemp) {
      temperature = temp;
      print('Temperature set to \$temperature°C');
    } else {
      print('Invalid temperature!');
    }
  }

  void showStatus() {
    String lightStatus = lightsOn ? "ON" : "OFF";
    String secStatus = securityArmed ? "ARMED" : "DISARMED";
    String mood = '';
    if (temperature % 3 == 0 && temperature % 5 == 0) mood = 'Perfect Day';
    else if (temperature % 3 == 0) mood = 'Cool Day';
    else if (temperature % 5 == 0) mood = 'Warm Day';

    print('\n--- System Status ---');
    print('Lights: \$lightStatus');
    print('Thermostat: \$temperature°C \$mood');
    print('Security: \${secStatus.toUpperCase()}');
  }
}


==============================
Budget Management (Dart)
==============================

import 'dart:io';

void main() {
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  while (true) {
    print('\n--- Budget Menu ---');
    print('1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Choose an option: ');
    String? choice = stdin.readLineSync();

    if (choice == '1') {
      stdout.write('Enter income description: ');
      String? desc = stdin.readLineSync();
      stdout.write('Enter amount: ');
      double? amount = double.tryParse(stdin.readLineSync() ?? '');
      if (amount != null && amount > 0) {
        incomeList.add({desc ?? '': amount});
        print('Income added.');
      } else {
        print('Invalid amount!');
      }
    } else if (choice == '2') {
      stdout.write('Enter expense description: ');
      String? desc = stdin.readLineSync();
      stdout.write('Enter amount: ');
      double? amount = double.tryParse(stdin.readLineSync() ?? '');
      if (amount != null && amount > 0) {
        expenseList.add({desc ?? '': amount});
        print('Expense added.');
      } else {
        print('Invalid amount!');
      }
    } else if (choice == '3') {
      double totalIncome = incomeList.fold(0, (sum, item) => sum + item.values.first);
      double totalExpenses = expenseList.fold(0, (sum, item) => sum + item.values.first);
      double net = totalIncome - totalExpenses;

      print('\n--- Summary ---');
      print('Total Income: \$\$totalIncome');
      print('Total Expenses: \$\$totalExpenses');
      if (net >= 0) {
        print('Net Profit: \$\$net');
        double tax = net > 0 ? net * 0.15 : 0;
        print('Tax to pay: \$\${tax.toStringAsFixed(2)}');
      } else {
        print('Net Loss: \$\${net.abs()}');
      }
    } else if (choice == '4') {
      print('Goodbye!');
      break;
    } else {
      print('Invalid choice!');
    }
  }
}