byte ledPin[] = {15, 14, 2, 3, 4, 5, 6, 7}; 
byte numPin;
int nut = 21;
bool run = 0;

void setup() 
{
  Serial.begin(9600);
  pinMode(nut, INPUT_PULLUP);
  numPin = sizeof(ledPin);
  for (int i = 0; i < numPin; i++)
  {
    pinMode(ledPin[i], OUTPUT);
  }
}

void loop() 
{
  if (digitalRead(nut)==0)
    { 
      run = !run; 
      Serial.write(run+48);
      while((digitalRead(nut)==0));
      delay(100);
    }


  if (run==1)
    {
      trai_phai();
      phai_trai();
    }
}

void trai_phai()
{
  for (int i = numPin-1; i > 0 ; i--)
    {digitalWrite(ledPin[i], HIGH);
    delay(100);
    digitalWrite(ledPin[i], LOW);
    }
}

void phai_trai()
{
  for (int i = 0; i < numPin-1; i++)
    {digitalWrite(ledPin[i], HIGH);
    delay(100);
    digitalWrite(ledPin[i], LOW);
    }
}