rgbledblink.cpp

uint8_t state = 0, s = 0;
uint8_t pin[] = { A4, A5, 2 };

void setup() {
}

void loop() {
  for (int i = 0; i < sizeof(pin); i++) {
    s = (state & (3 << (2 * i))) >> (2 * i);
    if (s == 2) {
      pinMode(pin[i], INPUT);
    } else if (s == 3) {
      pinMode(pin[i], INPUT_PULLUP);
    } else {
      pinMode(pin[i], OUTPUT);
      digitalWrite(pin[i], s);
    }
  }
  state++;
  delay(50);
}