int arr[] = {0,3,7,11};
void setup(){
  for (int i =0; i<4; ++i){
    pinMode(arr[i], OUTPUT);
  }
}

void bin(int i){
    for (int j = 0; j < sizeof(i) * 8; j++, i /= 2) {
        if (i % 2 == 1) {
            digitalWrite(arr[j], HIGH);
        }
    }
}

void inv(int pin) {
  int currentState = digitalRead(pin);
  digitalWrite(pin, !currentState);
}


void loop(){
  for (int k = 0; k < 16; k++){
    bin(k);
    delay(1000);

    for (int i = 0 ; i<4; i++){
      inv(arr[i]);
    }
    delay(2000);
    for (int i = 0 ; i<4; i++){
      digitalWrite(arr[i], LOW);
    }
    delay(1000);
  }
}