// Create a pointer to the pin powering each  LED and to the photoresistor
int red = 3;
int yellow = 5;
int green = 6;
int blue = 11;
int ldr = A0;

// Variable for reading the photoresistor status
int ldrState = 0;

void setup() {
  // Set the pins powering each LED to output mode
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(blue, OUTPUT);
  
  // Set the pin powering the photoresistor as an input
  pinMode(ldr, INPUT);

}

void loop() {
  // Read the state of the photoresistor
  ldrState = analogRead(ldr);

  // Check if the photoresistor is pressed. If it is, the ldrState is less than 250 in the conditions I am using.
  if (ldrState < 100) {
    // turn the LEDs on
    digitalWrite(red, HIGH);
    digitalWrite(yellow, HIGH);
    digitalWrite(green, HIGH);
    digitalWrite(blue, HIGH);
  }
  else {
    // turn the LEDs off
    digitalWrite(red, LOW);
    digitalWrite(yellow, LOW);
    digitalWrite(green, LOW);
    digitalWrite(blue, LOW);
  }

}