Untitled

#define trigPin 
#define echoPin 
#define buzzer 

void setup() {
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
    pinMode(buzzer, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    long duration;
    int distance;

    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.print(distance);
    Serial.println(" cm");

    if (distance <= 10) {
        tone(buzzer, 1000, 100);  
        delay(100);
    } else if (distance <= 20) {
        tone(buzzer, 1000, 200);
        delay(300);
    } else if (distance <= 30) {
        tone(buzzer, 1000, 300);
        delay(600);
    } else {
        noTone(buzzer);
    }
}