#define n_floors  5
#define upbtn 3
#define dwnbtn 2
#define upled 10
#define dwnled 4

bool upbtn_stat = LOW;
bool upbtn_prestat = HIGH;
bool dwnbtn_stat = LOW;
bool dwnbtn_prestat = HIGH;

int leds[n_floors] = {5,6,7,8,9};
unsigned int speed = 500;

void setup() {
  Serial.begin(9600);

  // Set all pins as digital outputs:
  for(int i = 0; i < n_floors; i++) {
    pinMode(i, OUTPUT);
    digitalWrite(i, LOW);
  }
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, 0);

  //Set buttons as inputs:
  pinMode(upbtn, INPUT_PULLUP);
  pinMode(dwnbtn, INPUT_PULLUP);
  pinMode(upled, OUTPUT);
  pinMode(dwnled, OUTPUT);

  digitalWrite(upled, LOW);
  digitalWrite(dwnled, LOW);
}

void loop() {
  if(upbtn_stat != upbtn_prestat && digitalRead(upbtn) == LOW){
    delay(100);
    digitalWrite(dwnled, LOW);
    digitalWrite(upled, HIGH);
    for(int l = 0; l < n_floors; l++){
      digitalWrite(leds[l],HIGH);
      delay(speed/6);
      digitalWrite(leds[l-1],LOW);
      delay(speed);
      }
    upbtn_prestat = !upbtn_stat;
  }
  if(dwnbtn_stat != dwnbtn_prestat && digitalRead(dwnbtn) == LOW){
    delay(100);
    digitalWrite(upled, LOW);
    digitalWrite(dwnled, HIGH);
    for(int l = n_floors - 1; l >= 0; l--){
      if (l == n_floors - 1){
        digitalWrite(n_floors, LOW);
        delay(speed);
      }else{
      digitalWrite(leds[l], HIGH);
      delay(speed/6);
      digitalWrite(leds[l+1], LOW);
      delay(speed);
      }
    }
    dwnbtn_prestat = !dwnbtn_stat;
  }
}