const int ledPins[] = { 0, 1, 2, 3, 4, 5};
const int buttonPins[] = {8, 9, 10, 11, 12, 13};

const int ledCount = 6;

void setup() {

  for (int i = 0; i < ledCount; i++) {
    pinMode(ledPins[i], OUTPUT);
    pinMode(buttonPins[i], INPUT_PULLUP);
  }

}

void loop() {

  bool buttonPressed = false;

  for (int i = 0; i < ledCount; i++) {

    if (digitalRead(buttonPins[i]) == LOW) { // Taster gedrückt
      digitalWrite(ledPins[i], HIGH);
      buttonPressed = true;
    } else {
      digitalWrite(ledPins[i], LOW);
    }

  }

  if (!buttonPressed) {
    for (int i = 0; i < ledCount; i++) {
      digitalWrite(ledPins[i], LOW);
    }
  }

}