const int target[] = {13, 12, 11, 10, 9};
const int sensor[] = {7, 6, 5, 4, 3};
const int hit = 2;
int rnd = 0;
unsigned long previousMillis = 0;        // will store last time LED was updated

const long interval = 2000;           // interval at which to blink (milliseconds)

void setup()
{
  for (int i = 0; i < 5; i++) {
    pinMode(target[i], OUTPUT);
    pinMode(sensor[i], INPUT);
  }
  pinMode(hit, OUTPUT);

  randomSeed(analogRead(0));
  rnd = random(1, 6);
  Serial.begin(9600);

}

void loop()
{

  unsigned long currentMillis = millis();
  Serial.println(rnd);

  if (currentMillis - previousMillis <= interval) {
    previousMillis = currentMillis;

    int shoot = digitalRead(sensor[rnd - 1]);

    if (shoot == HIGH) {

      digitalWrite(hit, HIGH);
      delay(500);
      digitalWrite(target[rnd - 1], LOW);
      digitalWrite(hit, LOW);
      rnd = random(1, 6);
    }

    else {
      digitalWrite(target[rnd - 1], HIGH);
      shoot = digitalRead(sensor[rnd]);

    }
  }
}