#include <Adafruit_NeoPixel.h> // https://github.com/adafruit/Adafruit_NeoPixel/

const byte pixCnt= 10;
const byte stripPin =2;

Adafruit_NeoPixel strip = Adafruit_NeoPixel(pixCnt, stripPin, NEO_GRB + NEO_KHZ800);


void setup() {
  strip.begin(); // initialize Neopixels
  strip.clear(); // clear pixel buffer
}

void loop() {

  for (int i = 0; i < 10; i++) {
    strip.setPixelColor(i, strip.Color(255, 0, 0));
    strip.show();
    strip.setPixelColor(i, strip.Color(0, 0, 0));
    delay(50);
  }
    for (int i = 8; i >= 0; i--) {
    strip.setPixelColor(i, strip.Color(255, 0, 0));
    strip.show();
    strip.setPixelColor(i, strip.Color(0, 0, 0));
    delay(50);
  }
}