const int leds[] = {2, 3, 4, 5, 6};

unsigned long previousMillis[] = {0, 0, 0, 0, 0};

// ALL VALUES ARE IN MILLISECONDS
const unsigned long intervals[] = {
  100,   // LED 1 → 100ms
  250,   // LED 2 → 250ms
  500,   // LED 3 → 500ms
  750,   // LED 4 → 750ms
  1000   // LED 5 → 1000ms
};

bool ledState[] = {LOW, LOW, LOW, LOW, LOW};

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

void loop() {
  unsigned long currentMillis = millis();

  for (int i = 0; i < 5; i++) {
    if (currentMillis - previousMillis[i] >= intervals[i]) {
      previousMillis[i] = currentMillis;
      ledState[i] = !ledState[i];
      digitalWrite(leds[i], ledState[i]);
    }
  }
}