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);
    }
  }
}