//Set the buzzer, green LED, and red LED pin numbers.
#define BUZZER_PIN 2
#define GREEN_LED_PIN 3
#define RED_LED_PIN 4

//Set up arrays for the melody notes.
int melody[] = {
   261, 196, 196, 220, 196, 0,
   247, 261
};
//Set up arrays for the note duration.
int noteDuration[] = {
   4, 4, 4, 4, 4, 4, 
   4, 4
};
//Set the following pins as output pins.
void setup() {
   pinMode(BUZZER_PIN, OUTPUT); //Sound Ouput(Buzzer sound)
   pinMode(GREEN_LED_PIN, OUTPUT); //Visual Output(Green LED light)
   pinMode(RED_LED_PIN, OUTPUT); //Visual Output(Red LED light)
}
//Loops the melody by performing each code inside.
void loop() {
   for (int i = 0; i < 8; i++) {
     int noteDurationMs = 1000 / noteDuration[i]; //Calculates note duration in milliseconds
     tone(BUZZER_PIN, melody[i], noteDurationMs); //Activates the buzzer

     digitalWrite(GREEN_LED_PIN, HIGH); //Turns on the green LED
     digitalWrite(RED_LED_PIN, LOW); //Turns off the red LED
     delay(noteDurationMs); //Pause for note duration
     noTone(BUZZER_PIN); //Turn off buzzer

     digitalWrite(GREEN_LED_PIN, LOW); //Turns off the green LED
     digitalWrite(RED_LED_PIN, HIGH); //Turns on the red LED
     delay(noteDurationMs); //Pause for note duration
   }
}