#define LED_1_PIN 11
#define LED_2_PIN 10
#define LED_3_PIN 9
#define LED_4_PIN 5
#define LED_5_PIN 3
#define LED_6_PIN 6
#define POTENTIOMETER_PIN A0
#define LED_NUMBER 6
byte LEDPinArray[LED_NUMBER] = { LED_1_PIN,
                                 LED_2_PIN,
                                 LED_3_PIN,
                                 LED_4_PIN,
                                 LED_5_PIN,
                                 LED_6_PIN };
                                
void initAllLEDs()
{
  for (int i = 0; i < LED_NUMBER; i++) {
    pinMode(LEDPinArray[i], OUTPUT);
  }
}
void setBrightnessForAllLEDs(int brightness)
{
  for (int i = 0; i < LED_NUMBER; i++) {
    analogWrite(LEDPinArray[i], brightness);
  }
}
void setup()
{
  initAllLEDs();
}
void loop()
{
  int potentiometerValue = analogRead(POTENTIOMETER_PIN);
  int brightness = map(potentiometerValue, 0, 1023, 0, 255);
  
  setBrightnessForAllLEDs(brightness);
}