int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9}; 
int ledCount = 8; 

void setup() {
  for (int i = 0; i < ledCount; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  // Soldan sağa
  for (int i = 0; i < ledCount; i++) {
    digitalWrite(ledPins[i], HIGH);
    delay(200);
    digitalWrite(ledPins[i], LOW);
  }

  // Sağdan sola
  for (int i = ledCount - 1; i >= 0; i--) {
    digitalWrite(ledPins[i], HIGH);
    delay(200);
    digitalWrite(ledPins[i], LOW);
  }
}