const int numLEDs = 4;
static int arr[5];
const int GPIO_Pins[] = {5, 4, 3, 2};

void setup() {
  // put your setup code here, to run once:
  for (int led = 0; led < numLEDs; led++)
  {
    pinMode(GPIO_Pins[led], OUTPUT);
    digitalWrite(GPIO_Pins[led],LOW);
  }
}
void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i <= 15; i++) {
    
      binaryLEDs(i);
      delay(2000);
  }
delay(3000);
}

void binaryLEDs(int num)
{ int original_num = num;
  for (int i = 0; i < 4; i++) {
    arr[i] = num % 2;
    num = num / 2;
    if (arr[i] == 1)
      digitalWrite(GPIO_Pins[i], HIGH);
    else
      digitalWrite(GPIO_Pins[i], LOW);
  }
delay(1000);
num = original_num;
 for (int i = 0; i < 4; i++) {
    arr[i] = num % 2;
    num = num / 2;
    if (arr[i] == 0)
      digitalWrite(GPIO_Pins[i], HIGH);
    else
      digitalWrite(GPIO_Pins[i], LOW);
  }
delay(1000);

}