const int buzzer = 3;
const int ledPin = 13;
const int songlength = 18;
char notes[] = "cdfda ag cdfdg gf";
int beats[] = {1, 1, 1, 1, 1, 1, 4, 4, 2, 1, 1, 1, 1, 1, 1, 1, 4, 4};
int tempo = 150;

void setup()
{
  pinMode(buzzer, OUTPUT);
  pinMode(ledPin, OUTPUT);
}

void loop()
{
  int i, duration;
  for (i = 0; i < songlength; i++) {
    duration = beats[i] * tempo;

    if (notes[i] == ' ') {
      delay(duration);
      digitalWrite(ledPin, LOW);
    } else {
      digitalWrite(ledPin, HIGH);
      tone(buzzer, frequency(notes[i]), duration);
      delay(duration);
    }

    
    delay(tempo );
  }
}

int frequency(char note) {
  int i;
  const int numNotes = 8;
  char names[] = {'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C'};
  int frequencies[] = {262, 294, 330, 349, 392, 440, 494, 523};
  for (i = 0; i < numNotes; i++) {
    if (names[i] == note) {
      return frequencies[i];  // Yes! Return the frequency
    }
  }
  return 0;
}