long dur;
long dist;
int buzzerPin = 13; 
int ledPin = 2; // <--- 1. Added LED variable

void setup() {
  Serial.begin(115200);
  pinMode(5, OUTPUT);   // Trig Pin
  pinMode(18, INPUT);   // Echo Pin
  pinMode(buzzerPin, OUTPUT); 
  pinMode(ledPin, OUTPUT); // <--- 2. Initialize the LED pin
}

void loop() {
  // Triggering the sensor
  digitalWrite(5, LOW);
  delayMicroseconds(2);
  digitalWrite(5, HIGH);
  delayMicroseconds(10);
  digitalWrite(5, LOW);
  
  dur = pulseIn(18, HIGH);
  dist = (dur * 0.0343) / 2;
  
  Serial.print("Distance: ");
  Serial.print(dist);
  Serial.println(" cm");

  // Buzzer & LED Logic
  if (dist > 0 && dist < 200) {
    digitalWrite(buzzerPin, HIGH); 
    digitalWrite(ledPin, HIGH);    // <--- 3. Turn LED ON
  } else {
    digitalWrite(buzzerPin, LOW);
    digitalWrite(ledPin, LOW);     // <--- 3. Turn LED OFF
  }
  
  delay(100); 
}