// Define the pins for the ultrasonic sensor
const int trigPin = 3;
const int echoPin = 2;

// Define the pins for the LEDs
const int led1Pin =11;
const int led2Pin = 10;
const int led3Pin = 9;

void setup() {
  // Set the pins for the ultrasonic sensor
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set the pins for the LEDs
  pinMode(led1Pin, OUTPUT);
  pinMode(led2Pin, OUTPUT);
  pinMode(led3Pin, OUTPUT);

  // Turn off all the LEDs initially
  digitalWrite(led1Pin, LOW);
  digitalWrite(led2Pin, LOW);
  digitalWrite(led3Pin, LOW);

  // Start the serial communication
  Serial.begin(9600);
}

void loop() {
  // Send a pulse to the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the distance from the ultrasonic sensor
  long duration = pulseIn(echoPin, HIGH);
  float distance = duration * 0.034 / 2;

  // Print the distance to the serial monitor
  Serial.print("Distance: ");
  Serial.println(distance);

  // Turn on the appropriate LED based on the distance
  if (distance < 100) {
    digitalWrite(led1Pin, HIGH);
    digitalWrite(led2Pin, LOW);
    digitalWrite(led3Pin, LOW);
  } else if (distance >= 100 && distance <= 200) {
    digitalWrite(led1Pin, LOW);
    digitalWrite(led2Pin, HIGH);
    digitalWrite(led3Pin, LOW);
  } else {
    digitalWrite(led1Pin, LOW);
    digitalWrite(led2Pin, LOW);
    digitalWrite(led3Pin, HIGH);
  }

  // Wait for a short period before taking the next measurement
  delay(100);
}