int distance;
int duration;
const int trigPin = 7;
const int echoPin = 6;
const int redPin = 13;
const int bluePin = 12;
const int yellowPin = 11;
void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
}

void loop() {
  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 is: ");
  Serial.println(distance);
  
  distanceQ();
 
}
void distanceQ()
{
  if (distance > 250)
  {
    digitalWrite(redPin, HIGH);
    digitalWrite(bluePin, LOW);
    digitalWrite(yellowPin, LOW);

  }else if (distance >= 100 && distance < 250)
  {
    digitalWrite(bluePin, HIGH);
    digitalWrite(redPin, LOW);
    digitalWrite(yellowPin, LOW);
  }else if (distance < 100)
  {
    digitalWrite(yellowPin, HIGH);
    digitalWrite(redPin, LOW);
    digitalWrite(bluePin, LOW);
  }
}