int binary[4] = {0};
short counter{};
int last_time_generate = 0;
int last_time_plus = 0;
int last_time_minus = 0;

void IRAM_ATTR generate_random() {
  if (millis() > last_time_generate + 150) {
    counter = random(0, 15);
    last_time_generate = millis();
  }
}

void IRAM_ATTR plus_random() {
  if (millis() > last_time_plus + 150) {
    counter++;
    last_time_plus = millis();
  }
}

void IRAM_ATTR minus_random() {
  if (millis() > last_time_minus + 150) {
    counter--;
    last_time_minus = millis();
  }
}

void setup() {
  pinMode(18, OUTPUT);
  pinMode(17, OUTPUT);
  pinMode(16, OUTPUT);
  pinMode(4, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(12), generate_random, RISING);
  attachInterrupt(digitalPinToInterrupt(14), plus_random, RISING);
  attachInterrupt(digitalPinToInterrupt(27), minus_random, RISING);
}


void copy_array(int arr1[], int arr2[], int length) {
  for (int i = 0; i < length; i++) {
      arr1[i] = arr2[i];
  }
}

void reverse(int arr[], int count) {
  int reversed[4];

  for (int i = 0, j = count; i < count; i++, j--) {
      reversed[i] = arr[j - 1];
  }

  copy_array(arr, reversed, count);
}

void decimal_to_binary(int decimal) {
  int remainder{}, number = decimal;

  for (int index = 0; index < 4; index++) {
      remainder = number % 2;
      number /= 2;

      binary[index] = remainder;
  }
  reverse(binary, 4);
}

int pins[4] = {18, 17, 16, 4};
void loop() {
  decimal_to_binary(counter);
  for (int i = 0; i < 4; i++) {
    digitalWrite(pins[i], binary[i]);
  }
}