const int row[3] = {
  21,19,18
};

const int col[3] = {
  33,25,26
};


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  for (int thisPin = 0; thisPin < 3; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    digitalWrite(col[thisPin], HIGH);
    digitalWrite(row[thisPin], LOW);
  }
}

void loop() {

  for (int i = 0; i < 3; i++) {
    digitalWrite(row[i],HIGH);
    for (int j = 0; j < 3; j++) {
      digitalWrite(col[j],LOW);
      delay(100);
      digitalWrite(col[j],LOW);
    }
    digitalWrite(row[i],LOW);
  }
  
  delay(0); // this speeds up the simulation
}