// Define the LED pins
int ledPins[] = {3, 5, 6, 9, 10, 11}; // Pins for 6 LEDs
int numLeds = 6;
int brightness = 0;
int fadeAmount = 5; // Fade increment

void setup() {
  Serial.begin(9600);
  // Set all LED pins as outputs
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  // Move the LEDs forward
  for (int i = 0; i < numLeds; i++) {
    // Fade in
    for (brightness = 0; brightness <= 255; brightness += fadeAmount) {
      analogWrite(ledPins[i], brightness);
      Serial.println(brightness);
      delay(100); // Delay for smooth fading
    }

    // Fade out
    for (brightness = 255; brightness >= 0; brightness -= fadeAmount) {
      analogWrite(ledPins[i], brightness);
      Serial.println(brightness);
      delay(100); // Delay for smooth fading
    }
  }

  // Move the LEDs backward
  for (int i = numLeds - 2; i >= 0; i--) {
    // Fade in
    for (brightness = 0; brightness <= 255; brightness += fadeAmount) {
      analogWrite(ledPins[i], brightness);
      Serial.println(brightness);
      delay(100); // Delay for smooth fading
    }

    // Fade out
    for (brightness = 255; brightness >= 0; brightness -= fadeAmount) {
      analogWrite(ledPins[i], brightness);
      Serial.println(brightness);
      delay(100); // Delay for smooth fading
    }
  }
}