// Pin definitions
const int ledPins[] = {9, 10, 11, 12};   // Pins for the 4 LEDs
const int incrementButtonPin = 7;     // Pin for the increment button
const int decrementButtonPin = 6;     // Pin for the decrement button
 
const int numLeds = 4;                // Number of LEDs
int counter = 0;                      // Initial counter value
 
void setup() {
  // Set LED pins as outputs
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  // Set button pins as inputs with pull-down resistors
  pinMode(incrementButtonPin, INPUT_PULLUP);
  pinMode(decrementButtonPin, INPUT_PULLUP);
  // Initialize LEDs
  updateLeds();
}
 
void loop() {
  Serial.println(counter);
  // Check if increment button is pressed
  if (digitalRead(incrementButtonPin) == LOW) {
    delay(50); // Debounce delay
    if (digitalRead(incrementButtonPin) == LOW) { // Check again
      counter++;
      if (counter > 15) { // Max count for 4 LEDs (binary 1111)
        counter = 0;
      }
      updateLeds();
      while (digitalRead(incrementButtonPin) == LOW); // Wait until button is released
    }
  }
 
  // Check if decrement button is pressed
  if (digitalRead(decrementButtonPin) == LOW) {
    delay(50); // Debounce delay
    if (digitalRead(decrementButtonPin) == LOW) { // Check again
      counter--;
      if (counter < 0) { // Min count
        counter = 15;
      }
      updateLeds();
      while (digitalRead(decrementButtonPin) == LOW); // Wait until button is released
    }
  }
}
 
void updateLeds() {
  // Update LED states based on counter value
  for (int i = 0; i < numLeds; i++) {
    if (bitRead(counter, i) == 1) {
      digitalWrite(ledPins[i], HIGH);
    } else {
      digitalWrite(ledPins[i], LOW);
    }
  }
}