// Forum: https://forum.arduino.cc/t/how-backwards-functions-in-code/1101167
// This Wokwi project: https://wokwi.com/projects/359042982266722305

const int LED_COUNT = 7;
int LED_PINS[LED_COUNT] = {3, 5, 6, 9, 10, 11};

int currentPosition = LED_COUNT - 2;
int delayTime = 100;
float brightness = 0.5;

void setup() {
  for (int i = 0; i < LED_COUNT; i++) {
    pinMode(LED_PINS[i], OUTPUT);
    // digitalWrite(LED_PINS[i], LOW);
  }
}

void loop() 
{
  if (currentPosition == LED_COUNT - 2) 
  {
    for (int i = LED_COUNT - 2; i >= 0; i--) 
    {
      analogWrite(LED_PINS[i], brightness * 255);
      delay(delayTime);
      digitalWrite(LED_PINS[i], LOW);
    }
  }

  for (int i = 0; i <= currentPosition; i++) 
  {
    analogWrite(LED_PINS[i], brightness * 255);
    delay(delayTime);
    digitalWrite(LED_PINS[i], LOW);
  }
  
  analogWrite(LED_PINS[currentPosition], brightness * 255);
  currentPosition--;
}