int redLED = 10;
int greenLED = 9;
int yellowLED = 8;

const int trigPin = 3;
const int echoPin = 5;
long duration;
int distance;

void setup() {
  // put your setup code here, to run once:
  for(int i = 7; i < 13; i++){
    pinMode(i, OUTPUT);
  }
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  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.println(distance);

  if(distance > 250){
  digitalWrite(redLED, HIGH);
  digitalWrite(greenLED, LOW);
  digitalWrite(yellowLED, LOW);
  }
  if(distance >= 100 && distance <= 250){
  digitalWrite(redLED, LOW);
  digitalWrite(greenLED, HIGH);
  digitalWrite(yellowLED, LOW);
  }
  if(distance < 100){
  digitalWrite(redLED, LOW);
  digitalWrite(greenLED, LOW);
  digitalWrite(yellowLED, HIGH);
  }
  
}