int ledPin[] = {13, 12, 11,10};
int ledDelay[4]={8000, 4000,2000, 1000};
// declare other required variables
unsigned long lastChangeTime[4];              
bool ledState[4] = {LOW, LOW, LOW, LOW};

void setup() {
  for(int i=0;i<4;i++){
    // initialize lastChangeTimes
    pinMode(ledPin[i], OUTPUT);
    digitalWrite(ledPin[i], ledState[i]);    
    lastChangeTime[i] = millis();
    // set pin mode for ledPins
    
  }
}


void loop() {
  // implement the toggling logic
  unsigned long currTime = millis();

   for (int i = 0; i < 4; i++) {
    if (currTime - lastChangeTime[i] >= ledDelay[i]) {
      ledState[i] = !ledState[i];             // Toggle LED state
      digitalWrite(ledPin[i], ledState[i]);   // Update LED
      lastChangeTime[i] = currTime;           // Reset timer
    }
   }
}