const int potpin = A0;
int ledcount = 10;
int ledpins[] = {2,3,4,5,6,7,8,9,10,11};
int potvalue = 0;

void setup() {
for (int thisled = 0; thisled < ledcount; thisled++){
  pinMode(ledpins[thisled], OUTPUT);
}
}

void loop() {
potvalue = analogRead(potpin);
potvalue = map(potvalue,0,1023,0,ledcount);

for (int thisled =0; thisled <ledcount; thisled++){
  if (thisled < potvalue){
    digitalWrite(ledpins[thisled],HIGH);
  }
  else{
    digitalWrite(ledpins[thisled],LOW);
  }
}
}