const int analogPin = A0;
const int ledCount = 9; 
int ledPins[] = {2,3,4,5,6,7,8,9,10};

void setup() {
  for (int thisLed = 0; thisLed < ledCount; thisLed++){
    pinMode(ledPins[thisLed], OUTPUT);
  }

}

void loop() {
  int sensorReading = analogRead(analogPin);
  
 
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);
  
  for (int thisLed = 0; thisLed < ledCount; thisLed++){
    if(thisLed < ledLevel){
      digitalWrite(ledPins[thisLed], HIGH);
    }else{
      digitalWrite(ledPins[thisLed], LOW);
    }
  }
}