#define NUM_LEDS 5 
int blinkPins[NUM_LEDS] = {2, 4, 5, 18, 19}; 
int delayTime = 250; 

void setup() {
  for (int i = 0; i < NUM_LEDS; i++) {
    pinMode(blinkPins[i], OUTPUT); 
  }
}


 void loop() {
  // Right to left
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(blinkPins[i], HIGH); 
    delay(delayTime);
    digitalWrite(blinkPins[i], LOW); 
  }

  // Left to right
  for (int i = NUM_LEDS - 1; i >= 0; i--) {
    digitalWrite(blinkPins[i], HIGH); 
    delay(delayTime);
    digitalWrite(blinkPins[i], LOW); 
  }}