int ledPins[] = {23, 22, 21, 19, 18, 5, 4, 2};

void setup() {
    // Initialize each pin as an output:
    for (int pin = 0; pin < 8; pin++) {
        pinMode(ledPins[pin], OUTPUT);
    }
}

void loop() {
    // Move two LEDs from left to right:
    for (int pin = 0; pin < 7; pin++) { // Stop at the second-to-last LED
        digitalWrite(ledPins[pin], HIGH); // Turn the current LED on
        digitalWrite(ledPins[pin + 1], HIGH); // Also turn the next LED on
        delay(150);                         // Wait for 150 milliseconds
        digitalWrite(ledPins[pin], LOW);    // Turn the current LED off
    }
    digitalWrite(ledPins[7], LOW); // Ensure the last LED is turned off after the loop
    
    // Pause at the end before moving back
    delay(300);
    
    // Move two LEDs from right to left:
    for (int pin = 6; pin > 0; pin--) { // Start from the second-to-last LED
        digitalWrite(ledPins[pin], HIGH); // Turn the current LED on
        digitalWrite(ledPins[pin - 1], HIGH); // Also turn the previous LED on
        delay(150);                         // Wait for 150 milliseconds
        digitalWrite(ledPins[pin], LOW);    // Turn the current LED off
    }
    digitalWrite(ledPins[0], LOW); // Turn off the first LED after finishing the loop to the left
    
    // Pause at the end before restarting the animation
    delay(300);
}