const int buttonPin = 27; // Button pin
const int ledPins[] = {26, 0, 1}; // LED pins
const int numLeds = 3; // Number of LEDs
int ledIndex = 0; // Current LED index
bool previousButtonState = HIGH; // Previous button state, assuming pull-up

void setup() {
  for (int i = 0; i < numLeds; i++) 
  {
    pinMode(ledPins[i], OUTPUT); // Initialize LED pins as output
  }
  pinMode(buttonPin, INPUT_PULLUP); // Initialize button pin as input with pull-up resistor
}

void loop() {
  bool currentButtonState = digitalRead(buttonPin);
  if (currentButtonState == LOW && previousButtonState == HIGH) {
    // Button was pressed
    blinkLedsRecursively(0); // Start blinking sequence
  }
  previousButtonState = currentButtonState; // Update the previous button state
}

void blinkLedsRecursively(int index) //recursive function
{
  if (index >= numLeds) return; // Base case: stop if past the last LED
  
  digitalWrite(ledPins[index], HIGH); // Turn on current LED
  delay(500); // Wait for half a second
  digitalWrite(ledPins[index], LOW); // Turn off current LED
  
  blinkLedsRecursively(index + 1); // Recursively call for the next LED
}