#define trigPin 7
#define echoPin 6
#define LEDlampRed 8
#define LEDlampYellow 9
#define LEDlampGreen 10

long duration;
int distance;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(LEDlampRed, OUTPUT);
pinMode(LEDlampYellow, OUTPUT);
pinMode(LEDlampGreen, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
long duration, distance;
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin, HIGH);
distance = duration*0.0344/2;

if (distance > 100) {
  digitalWrite(LEDlampGreen, HIGH);
  digitalWrite(LEDlampYellow, LOW);
  digitalWrite(LEDlampRed, LOW);
}

else if (distance >= 50) {
  digitalWrite(LEDlampGreen, LOW);
  digitalWrite(LEDlampYellow, HIGH);
  digitalWrite(LEDlampRed, LOW);
}

else
{
  digitalWrite(LEDlampGreen, LOW);
  digitalWrite(LEDlampYellow, LOW);
  digitalWrite(LEDlampRed, HIGH);
}

Serial.print("distance: ");
Serial.print(distance);
Serial.println("cm");
delay(100);
}