int j [3] = {2, 4, 6}; //trig pins
int k [3] = {3, 5, 7}; // echo pins
# define led 10
# define rele 11
# define buzzer 12
int buzzerState = 0;
int distance0;
int distance1 ;
int distance2 ;



void setup()
{
  Serial.begin(115200);
  // put your setup code here, to run once:
  for (int trigPin : j)
  {
    pinMode (trigPin, OUTPUT );
  }
  for  (int echoPin : k)
  {
    pinMode(echoPin, INPUT);
  }
  pinMode(led, OUTPUT);
  pinMode(rele, OUTPUT);
  pinMode(buzzer, OUTPUT);
}

void loop () {
  distanceUpdate();
  // check distance, set LED and relay and maybe launch a tone burst
  if ((distance0 < 4 || distance1 < 4 || distance2 < 4 ) && buzzerState==0)
  {
   // if (buzzerState == 0 ) {

      digitalWrite(led, HIGH);
      digitalWrite(rele, LOW);
      buzzerState = 1;    // no more tone until we've seen the distnace go > 10
      for (int i = 0; i < 5; i++) {
        distanceUpdate();
        if (distance0 > 9 && distance1 > 9 && distance2 > 9 ) {
          break;
        }

        tone(buzzer, 2500); // hearing this better at 1000 Hz

        delay(200);

        noTone(buzzer);
        delay(200);
      }

     
  }

  if (distance0 > 9 && distance1 > 9 && distance2 > 9 )
  {

    //    noTone(buzzer);  would immediately stop buzzer

    buzzerState = 0;  // allow again the tone to trigger on
    Serial.print("buzzerState:");
    Serial.println(buzzerState);

    digitalWrite(led, LOW);

    digitalWrite(rele, HIGH);

  }

}

int distanceUpdate() {
  distance0 = getEcho(2, 3);
  distance1 = getEcho(4, 5);
  distance2 = getEcho(6, 7);
  Serial.println(distance0);
  Serial.println(distance1);
  Serial.println(distance2);
}
long getEcho(int trigPin, int echoPin)

{

  long duration, distance;



  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);



  distance = (duration / 2) / 29.1;



  return distance;

}

/*
  int j [3] = {2, 4, 6}; //trig pins
  int k [3] = {3, 5, 7}; // echo pins
  # define led 10
  # define rele 11
  # define buzzer 12
  int buzzerState = 0;
  int distance0;
  int distance1 ;
  int  distance2 ;



  void setup()
  {
  Serial.begin(115200);
  // put your setup code here, to run once:
  for (int trigPin : j)
  {
    pinMode (trigPin, OUTPUT );
  }
  for  (int echoPin : k)
  {
    pinMode(echoPin, INPUT);
  }
  pinMode(led, OUTPUT);
  pinMode(rele, OUTPUT);
  pinMode(buzzer, OUTPUT);
  }

  void loop()

  { delay(500);

  long distance0, distance1, distance2;
  distance0 = getEcho(2, 3);
  distance1 = getEcho(4, 5);
  distance2 = getEcho(6, 7);
  Serial.println(distance0);
  Serial.println(distance1);
  Serial.println(distance2);
  // currentMillis = millis(); you are using delay

  // check distance, set LED and relay and maybe launch a tone burst
  if ((distance0 < 4 || distance1 < 4 || distance2 < 4 ) && buzzerState == 0 )
  {

    digitalWrite(led, HIGH);
    digitalWrite(rele, LOW);
    buzzerState = 1;    // no more tone until we've seen the distnace go > 10
    for (int i = 0; i < 5; i++) {


      tone(buzzer, 2500); // hearing this better at 1000 Hz

      delay(500);

      noTone(buzzer);
      delay(500);


    }
  }

  if (distance0 > 9 && distance1 > 9 && distance2 > 9 )
  {

    //    noTone(buzzer);  would immediately stop buzzer

    buzzerState = 0;
    Serial.print("buzzerState:");
    Serial.println(buzzerState);  // allow again the tone to trigger on

    digitalWrite(led, LOW);

    digitalWrite(rele, HIGH);

  }

  }

  long getEcho(int trigPin, int echoPin)

  {

  long duration, distance;



  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);



  distance = (duration / 2) / 29.1;



  return distance;

  }*/