#define NUM_LEDS 10
int ledPins[NUM_LEDS] = {2, 4, 5, 18, 19, 21, 22, 23, 25, 26};
#define BUTTON_PIN 15

int currentLED = 0, direction = 1;

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

void loop() {
  if (!digitalRead(BUTTON_PIN)) {
    direction = -direction;
    delay(200);  // Debounce
  }

  digitalWrite(ledPins[currentLED], HIGH);
  delay(200);
  digitalWrite(ledPins[currentLED], LOW);

  currentLED = (currentLED + direction + NUM_LEDS) % NUM_LEDS;  // วนกลับเมื่อเกินขอบเขต
}