int ledPin[] = {13, 12, 11,10};
int ledDelay[4]={8000, 4000,2000, 1000};
// declare other required variables
int ledtime[4]={0,0,0,0};
int ledstate[]={LOW,LOW,LOW,LOW};
void setup() {
  int currTime =0;
  for(int i=0;i<4;i++){
    // initialize lastChangeTimes
   pinMode(ledPin[i], OUTPUT);
    // set pin mode for ledPins
    
  }
}


void loop() {
 int  currTime =millis();
  // implement the toggling logic
  for (int i=0; i<4; i++)
  {
    if (currTime - ledtime[i] >= ledDelay[i])
    {   
       ledstate[i] = !ledstate[i];
      digitalWrite(ledPin[i], ledstate[i]);

      ledtime[i]=currTime;
    }
  }
}