#include <Arduino.h>

int pins[] {23,22,21,19};
const int NUMBER_OF_PINS = sizeof(pins)/sizeof(pins[0]);
const int NUMBER_OF_LEDS = NUMBER_OF_PINS * (NUMBER_OF_PINS-1);
byte pairs[NUMBER_OF_LEDS/2][2] = {{0,1}, {1,2}, {0,2}, {2,3}, {1,3}, {0,3} };


void setup() { 
  // put your setup code here, to run once:
  Serial.begin(115200);
  while(!Serial);
  Serial.println("Hello, ESP32!");
  Serial.println(String(NUMBER_OF_PINS));
  Serial.println(String(NUMBER_OF_LEDS));
}

void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i < NUMBER_OF_LEDS;i++){
    lightLed(i);
    delay(300);
  }

}






void lightLed(int led){
  int indexA = pairs[led/2][0];
  int indexB = pairs[led/2][1];
  int pinA = pins[indexA];
  int pinB = pins[indexB];

  for (int i = 0; i < NUMBER_OF_PINS;i++){
    if (pins[i] != pinA && pins[i] != pinB){
      pinMode(pins[i], INPUT);
      digitalWrite(pins[i], LOW);
    }
  pinMode(pinA, OUTPUT);
  pinMode(pinB, OUTPUT);
  }
  if (led % 2 == 0){
    digitalWrite(pinA, LOW);
    digitalWrite(pinB, HIGH);
  }
  else
  {
    digitalWrite(pinA, HIGH);
    digitalWrite(pinB, LOW);
  }
}