int echo= 7;
int trig= 6;
int led1= 3;
int led2= 2;
int led3= 1;

void setup()
{
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
}

float ultrasonik()
{
digitalWrite(trig, LOW);
delayMicroseconds (2);
digitalWrite(trig, HIGH);
delayMicroseconds (10);
digitalWrite(trig, LOW);
int durasiPantulan= pulseIn (echo, HIGH);
return durasiPantulan * 0.034 / 2;
}

void loop()
{
float jarak = ultrasonik();
if(jarak>100)
{
digitalWrite(led1, HIGH);
digitalWrite(led2, LOW);
}
else if
(jarak<=100 && jarak>50)
{
digitalWrite(led2, HIGH);
digitalWrite(led1, LOW);
digitalWrite(led3, LOW);
}
else if(jarak<=50)
{
digitalWrite(led3, HIGH);
digitalWrite(led2, LOW);
}
}