int LEDS[] = {15, 2, 4, 5, 18};
int qtdLeds = sizeof(LEDS) / sizeof(LEDS[0]);
int switchPin = 19;

void setup() {
  for(int i = 0; i < qtdLeds; i++) {
    pinMode(LEDS[i], OUTPUT);
  }
  pinMode(switchPin, INPUT);
}

void loop() {

  int swicthState = digitalRead(switchPin);

  if(swicthState == HIGH) {
    for(int i = 0; i < qtdLeds; i++) {
      digitalWrite(LEDS[i], HIGH);
      delay(1000);
      digitalWrite(LEDS[i], LOW);
    }

    for(int i = (qtdLeds - 2); i > 0; i--) {
      digitalWrite(LEDS[i], HIGH);
      delay(1000);
      digitalWrite(LEDS[i], LOW);
    }
  } else {
    for(int i = 0; i < qtdLeds; i++) {
      digitalWrite(LEDS[i], LOW);
    }
  }

}