int led[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int jumlahLed = 10;
void setup() {
  for (int i = 0; i < jumlahLed; i++) {
    pinMode(led[i], OUTPUT);
  }
}
void loop() {
  for (int i = 0; i < jumlahLed; i++) {
    nyalakanSatuLampu(i);
    delay(50);
  }
  for (int i = jumlahLed - 2; i > 0; i--) {
    nyalakanSatuLampu(i);
    delay(50);
  }
}
void nyalakanSatuLampu(int indeks) {
  for (int i = 0; i < jumlahLed; i++) {
    digitalWrite(led[i], i == indeks ? HIGH : LOW);
  }
}