//Created by Barbu Vulc!
//Special thanks to @Kouzone (Discord) for help!
const int  // the input pins (as buttons)
  b1 = A0, // blue button
  b2 = A1; // red button

byte leds[] = {
  // list of pins assigned to
  // leds; therefore you don't
  // need to change the entire
  // code if you plan to change
  // the pin destinations later
  5, 6, 7, 8, 9, 10, 11, 12,
};

void setLeds(long pattern){
  // this um, sorta hard to explain
  // how it works, but basically
  // just set the leds all at once
  // according to the 'pattern',
  // inputting em as binary format
  // like 0b10101010 makes your
  // life easier here!

  for(int k=0; k<sizeof(leds); k++){
    digitalWrite(leds[k],pattern & 1);
    pattern = pattern >> 1;
  }
}

void setup(){
  //LEDs & buttons initalization...
  for(int k=0; k<sizeof(leds); k++){
    // make assigned pins as output
    // hence to connect to their leds
    pinMode(leds[k], OUTPUT);
  }

  // buttons, uh
  pinMode(b1,INPUT); // blue
  pinMode(b2,INPUT); // red
}

void loop(){
    bool b1st = digitalRead(b1); // read blue button
    bool b2st = digitalRead(b2); // read red button
    byte state = b1st +  b2st*2;
    // put into switch state
    // (this is better than if-else, for this case)
    switch(state){
      case 0: // state == 0
        setLeds(0b00001111);
      break;
      case 1: // state == 1
        setLeds(0b11110000);
      break;
      case 2: // state == 2
        setLeds(0b00111100);
      break;
      case 3: // state == 3
        setLeds(0b11000011);
      break;
    }
    
    // actually it seem i understood how these states
    // are composed logically, therefore all of them
    // could be represented only as
    //setLeds(0b00001111 ^ 0b11111111*b1st ^ 0b00110011*b2st );
    // if you're gonna use the switch(state) version
    // comment this code first.
}