// Define LED pins
const int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11};

// Define buzzer pin
const int buzzerPin = 12;

void setup() {
  // Initialize the LED pins as outputs
  for (int i = 0; i < 10; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  
  // Initialize the buzzer pin as an output
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  // Turn on LEDs one by one with a delay and play buzzer
  for (int i = 0; i < 10; i++) {
    digitalWrite(ledPins[i], HIGH); // Turn on LED
    tone(buzzerPin, 1000);          // Play buzzer
    delay(100);                     // Wait for 100 milliseconds
    digitalWrite(ledPins[i], LOW);  // Turn off LED
    noTone(buzzerPin);              // Stop buzzer
  }
  
  // Turn on LEDs in reverse order with a delay and play buzzer
  for (int i = 9; i >= 0; i--) {
    digitalWrite(ledPins[i], HIGH); // Turn on LED
    tone(buzzerPin, 1500);          // Play buzzer
    delay(100);                     // Wait for 100 milliseconds
    digitalWrite(ledPins[i], LOW);  // Turn off LED
    noTone(buzzerPin);              // Stop buzzer
  }
  
  // Small delay before next cycle
  delay(50);
}