const int pin = A0;
const int ledCount = 5;

int leds[] = {
  0, 1, 2, 3, 4
};

void setup() {
  // put your setup code here, to run once:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(leds[thisLed], OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  int sensorReading = analogRead(pin);
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    if (thisLed < ledLevel) {
      digitalWrite(leds[thisLed], HIGH);
    }
    else {
      digitalWrite(leds[thisLed], LOW);
    }
  }
}