const int trig = 3;
const int echo = 2;

const int LED1 = 5;
const int LED2 = 6;
const int LED3 = 7;
const int LED4 = 8;

int duration = 0;
int distance = 0;

void setup() 
{
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);
  Serial.begin(9600);
}

void loop()
{
  digitalWrite(trig, HIGH);
  delayMicroseconds(1000);
  digitalWrite(trig, LOW);

  duration = pulseIn(echo, HIGH);
  distance = duration / 500.0;  // Adjusted the conversion factor for more accuracy
  //Serial.println(distance);

  updateLED(LED1, 30);
  updateLED(LED2, 20);
  updateLED(LED3, 10);
  updateLED(LED4, 5);
  Serial.println(" ");
}

void updateLED(int ledPin, int threshold)
{
  digitalWrite(ledPin, distance <= threshold);
}