int led[5]={13,12,11,6,2};

void setup() {
  for(int i=0; i<=4; i++){
     pinMode(led[i],OUTPUT);  
  }
}

void loop() {
  // Running LED left to right
  for(int i=0; i<=4; i++){
    digitalWrite(led[i],HIGH);
    delay(200);
    digitalWrite(led[i],LOW);
    delay(200);
  }

for(int i=3; i>=1; i--){
  // Running led right to left
    digitalWrite(led[i],HIGH);
    delay(200);
    digitalWrite(led[i],LOW);
    delay(200);
  }

}