const int ledCount = 10;    // the number of LEDs in the bar graph


int ledPins[] = {
  2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};   // an array of pin numbers to which LEDs are attached


void setup() {
  // put your setup code here, to run once:
    // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
    // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
      digitalWrite(ledPins[thisLed], HIGH);
      delay(200);
  }
   for (int thisLed = ledCount; thisLed >= 0; thisLed--) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
      digitalWrite(ledPins[thisLed], LOW);
      delay(200);
  }
  delay(200);
}