int led[]={0,1,2,3,4,5,6,7};
int tombol=8;
int i, val;

void setup(){
  pinMode(tombol,INPUT);

  for(i=0; i<8; i++){
    pinMode(led[i], OUTPUT);
  }
}

void loop(){
  val = digitalRead(tombol);
  if (val == 0) {
    for(i=7; i>=0; i--){
    digitalWrite(led[i], LOW);
    delay(100);
    }
    for(i=0; i<8; i++){
    digitalWrite(led[i], HIGH);
    delay(100);
    }
  }
  else{
    for(i=0; i<8; i++){
      digitalWrite(led[i], LOW);
     delay(100);
    }
    for(i=7; i>=0; i--){
      digitalWrite(led[i], HIGH);
      delay(100);
    }
  }
}