int buzzer = 1;
int outSensor = 2;
int inSensor = 3;
int green = 4;
int yellow = 5;
int red = 6;

int duration;
int distance;
int interval;

void setup() {
  pinMode(buzzer, OUTPUT);
  pinMode(outSensor, OUTPUT);
  pinMode(inSensor, INPUT);

  pinMode(green, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(red, OUTPUT);
}

void loop() {
  LED_controller();
  ultrasonic_sensor();
  interval = map(distance, 10, 400, 10, 700);  
}

void ultrasonic_sensor()
{
  digitalWrite(outSensor, HIGH);
  delayMicroseconds(10);
  digitalWrite(outSensor, LOW);

  duration = pulseIn(inSensor, HIGH);
  distance = duration/58;
}

void LED_controller()
{
    if(distance <= 350)
  {
     tone(buzzer, 1000, 100);
     delay(interval);
     digitalWrite(buzzer, LOW);
     delay(interval);
  }
  else
  {
    digitalWrite(buzzer, LOW);
  }

  if(distance <= 350 && distance >= 250)
  {
    digitalWrite(green, HIGH);
    digitalWrite(yellow,LOW);
    digitalWrite(red, LOW);
  }
  else if(distance < 250 && distance >= 150)
  {
    digitalWrite(green, LOW);
    digitalWrite(yellow,HIGH);
    digitalWrite(red, LOW);
  }
  else if(distance < 150 && distance >= 0)
  {
    digitalWrite(green, LOW);
    digitalWrite(yellow,LOW);
    digitalWrite(red, HIGH);
  }
  else
  {
    digitalWrite(green, LOW);
    digitalWrite(yellow, LOW);
    digitalWrite(red, LOW);
  }
}