#define LED_L 10
#define DelayTime 10
#define LIGHT 0
#define DARK 1
#define MIN 1
#define MAX 8
#define DT 40
const int Led[LED_L] = { 2,3,4,5,6,7,8,9,10,11 };

int buffer[LED_L];
int st, stL, dx, dy;

void setup() {
  st = 0;stL = MIN; dy = 1;dx = 1;
  for (int i = 0;i<LED_L;i++) {
    pinMode(Led[i], OUTPUT);
    digitalWrite(Led[i], DARK); //先讓 LED 初始值為暗
    buffer[i] = DARK;
  }
}

void loop() {
  int i, j, k, t;
  mov(st, stL);
  prn();
  delay(DelayTime+stL*DT);
  st += dx;
  if ((st < 0) || (st >= (LED_L - stL + 1))) {
     st -= dx;
     dx *= -1;
     //st += dx;
     stL+=dy;
     if(st >= (LED_L - stL + 1)) st = (LED_L - stL );
     if(stL>MAX){
      stL=MAX-1;
      dy=-1;
     }
     if(stL<MIN){
      stL=MIN+1;
      dy=1;
     }
   }
}

void mov(int a,int b) {
  for (int i = 0;i < LED_L;i++)
    buffer[i] = ( ((i >= a) && (i < a + b)) ? LIGHT : DARK );
}

void prn() {
  for(int i=0; i<LED_L; i++)
    digitalWrite(Led[i], buffer[i]);
}