LDR

const int LED = 9;
const int LDR = A0;

void setup() {
  pinMode(LED, OUTPUT);
}

void loop() {
  int a0 = analogRead(LDR);
  int light = max(map(a0, 0, 600, 1023, 0), 0);
  analogWrite(LED, light);
  delay(300);
}