int led[] = {4,5, 6, 7, 8, 9, 10, 11, 12, 13};
int jumlah = 10;
void setup() {
  for (int i = 0; i < jumlah; i++) {
    pinMode(led[i], OUTPUT);
  }
}
void loop() {
  for (int i = 0; i < jumlah; i++) {
    nyala(i);
  }  for (int i = jumlah - 2; i > 0; i--) {
    nyala(i);
  }
}void nyala(int index) {
  for (int i = 0; i < jumlah; i++) {
    digitalWrite(led[i], LOW);
  }
  digitalWrite(led[index], HIGH);
  delay(150);
}