#include <Adafruit_NeoPixel.h>
Adafruit_NeoPixel pix(20, 2, NEO_GRB + NEO_KHZ800);
void setup()
{
 pix.begin();
 pix.setBrightness(255);
 pinMode(8, INPUT_PULLUP);
 pinMode(9, INPUT_PULLUP);
}
void loop()
{
 if(digitalRead(8) == LOW)
 {
 for(int i=0; i<20; i++)
 pix.setPixelColor(i, pix.Color(0, 255, 0));
 pix.show();
 }
 else if(digitalRead(9) == LOW)
 {
 for(int i=0; i<20; i++)
 pix.setPixelColor(i, pix.Color(255, 0, 0));
 pix.show();
 delay(500);

 for(int i=19; i>=0; i--)
 pix.setPixelColor(i, pix.Color(0, 0, 255));
 pix.show();
 delay(500);
 }
 else
 {
 pix.clear();
 pix.show();
 }
}