const int trigPin = 2;  
const int echoPin = 3;  
const int ledPins[] = {4, 5, 6, 7, 8, 9, 10, 11, 12, 13};  
void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  for (int i = 0; i < 8; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  long duration, distance;
  
  
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  
  duration = pulseIn(echoPin, HIGH);
  
 
  distance = duration * 0.034 / 2;
  
  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  
  updateLEDBarGraph(distance);

  delay(500);  
}

void updateLEDBarGraph(int distance) {
  
  int numLEDs = distance / 13;  
  
 
  for (int i = 0; i < 13; i++) {
    digitalWrite(ledPins[i], i < numLEDs ? HIGH : LOW);
  }
}