// ---
// Aplikasi untuk menampilkan LED secara bergantian
// secara maju dan mundur
//
// Penanganan dengan if-else bertingkat
// ---
const int PIN_4 = 4;
const int PIN_5 = 5;
const int PIN_6 = 6;
const int PIN_7 = 7;
const int PIN_8 = 8;
const int PIN_9 = 9;
const int PIN_10 = 10;
const int PIN_11 = 11;
const int PIN_12 = 12;
const int PIN_13 = 13;

int arah = 1;
int indeksled = 0;

void setup()
{
 pinMode(PIN_4, OUTPUT);
 pinMode(PIN_5, OUTPUT);
 pinMode(PIN_6, OUTPUT);
 pinMode(PIN_7, OUTPUT);
 pinMode(PIN_8, OUTPUT);
 pinMode(PIN_9, OUTPUT);
 pinMode(PIN_10, OUTPUT);
 pinMode(PIN_11, OUTPUT);
 pinMode(PIN_12, OUTPUT);
 pinMode(PIN_13, OUTPUT);
}

void loop()
{
  int pin;
  if (indeksled == 0)
  pin = PIN_13;
  else
  if (indeksled == 1)
  pin = PIN_12;
  else
  if (indeksled == 2)
  pin = PIN_11;
  else
  if (indeksled == 3)
  pin = PIN_10;
  else
  if (indeksled == 4)
  pin = PIN_9;
  else
  if (indeksled == 5)
  pin = PIN_8;
  else
  if (indeksled == 6)
  pin = PIN_7;
  else
  if (indeksled == 7)
  pin = PIN_6;
  else
  if (indeksled == 8)
  pin = PIN_5;
  else
  pin = PIN_4;

  // Nyalakan LED dan kemudian matikan
  digitalWrite(pin, HIGH);
  delay(2000);
  digitalWrite(pin, LOW);

  // atur arah
  if (indeksled == 9)
  arah = -1;
  else
  if (indeksled == 0)
  arah = -1;

  indeksled = indeksled + arah;
}