int led[10] = {13, 12, 11, 10, 9, 8, 7, 6, 5, 4};

void setup() {
  for (int i = 0; i < 10; i++) {
    if (i % 2 == 0) {
      for(int j = 0; j < 10; j++){
        if(j % 2 == 0){
          digitalWrite(led[j], HIGH);
        } else {
          digitalWrite(led[j], LOW);
        }
      }
    }
    else {
      for(int j = 0; j < 10; j++){
        if(j % 2 == 1){
          digitalWrite(led[j], HIGH);
        } else {
          digitalWrite(led[j], LOW);
        }
      }
    }
    delay(1000);
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}