void setup() {
  for (int i = 12; i >= 6; i--) {
    pinMode(i, OUTPUT);
    digitalWrite(i, HIGH);
  }
}

void loop() {
  int duration = 300;
  //1
  for (int i = 12; i >= 6; i--) {
    digitalWrite(i, LOW);
    delay(duration);
    digitalWrite(i, HIGH);
  }
  delay(duration);
  //两边到中间
  for (int i = 0; i < 7; i++) {
    digitalWrite(12 - i, LOW);
    digitalWrite(6 + i, LOW);
    delay(duration);
    digitalWrite(12 - i, HIGH);
    digitalWrite(6 + i, HIGH);
  }
  delay(duration);
  //奇数
  for (int i = 12; i >= 6; i -= 2) {
    digitalWrite(i, LOW);
    delay(duration);
    digitalWrite(i, HIGH);
  }
  delay(duration);
  //偶数
  for (int i = 11; i >= 6; i -= 2) {
    digitalWrite(i, LOW);
    delay(duration);
    digitalWrite(i, HIGH);
  }
  delay(duration);
  //奇数all
  for (int i = 12; i >= 6; i -= 2) {
    digitalWrite(i, LOW);
  }
  delay(duration);
  for (int i = 12; i >= 6; i -= 2) {
    digitalWrite(i, HIGH);
  }
  delay(duration);
  //偶数all
  for (int i = 11; i >= 6; i -= 2) {
    digitalWrite(i, LOW);
  }
  delay(duration);
  for (int i = 11; i >= 6; i -= 2) {
    digitalWrite(i, HIGH);
  }
  delay(duration);
}