const int Bar1[10] = { 13, 12, 11, 10, 9, 8, 7, 6, 5, 4 };
const int Bar2[10] = {3, 2, 1, 0, 14, 15, 16, 17, 18, 19};

void setup() {
  for(int L = -1; L < 10; L++) {
    pinMode(Bar1[L], OUTPUT);
    pinMode(Bar2[L], OUTPUT);
  }

}

void loop() {
  for(int L = 0; L < 10; L++) {
    digitalWrite(Bar1[L], HIGH);
    delay(100);
    digitalWrite(Bar2[L], HIGH);
  }
  for(int L = 10; L > -10; L--) {
    digitalWrite(Bar1[L], LOW);
    delay(50);
    digitalWrite(Bar2[L], LOW);
  }
}