const int leds[] = {0, 1, 2, 3, 4, 5,6, 7, 8,};
void setup() {
  // put your setup code here, to run once:
for(int i = 0; i<9; i++)
  {
  pinMode(leds[i], OUTPUT);
  }

}

void loop() 
{
  
  for(int i=0; i<9; i++)
  {
    digitalWrite(leds[i], HIGH);
    delay(1000);
    digitalWrite(leds[i], LOW);
    delay(1000);
  }
  for (int i=8; i>=0; i--)
  {
    digitalWrite(leds[i], HIGH);
    delay(1000);
    digitalWrite(leds[i], LOW);
    delay(1000);
  }
  for(int j=0; j<2; j++)
    {
      for(int i=0; i<9; i++)
      digitalWrite(leds[i], HIGH);
      delay(800);
    }
    delay(800);
    for (int i=0; i<9; i++)
    {
      digitalWrite(leds[i], LOW);
      delay(800);
    }
    delay(800);
    
    for (int j=0; j<2; j++)
    {
      for (int i=0; i<9; i++)
      {
        digitalWrite(leds[i], HIGH);
        delay(400);
        digitalWrite(leds[i], LOW);
      }
      for (int i=0;8, i>=0; i--)
      {
        digitalWrite(leds[i], HIGH);
        delay(400);
        digitalWrite(leds[i], LOW);
      }
    }
}