if-then-else

If touched: blink pin 13. Else: blink pin 7.

const int TOUCH_SENSOR_PIN = 2;
const int LED_1_PIN = 13;
const int LED_2_PIN = 7;

void setup() {
  pinMode(TOUCH_SENSOR_PIN, INPUT);
  pinMode(LED_1_PIN, OUTPUT);
  pinMode(LED_2_PIN, OUTPUT);
}

void loop() {
  if (digitalRead(TOUCH_SENSOR_PIN) == HIGH) {
    digitalWrite(LED_2_PIN, LOW);

    digitalWrite(LED_1_PIN, HIGH);
    delay(500);
    digitalWrite(LED_1_PIN, LOW);
    delay(500);
  } else {
    digitalWrite(LED_1_PIN, LOW);

    digitalWrite(LED_2_PIN, HIGH);
    delay(500);
    digitalWrite(LED_2_PIN, LOW);
    delay(500);
  }
}

Hit ✓ Check → Hit → Upload → Touch the sensor.

One sensor. Two choices.

Add the second LED: pin 7 → 220 Ω resistor → LED long leg; short leg → GND. Each external LED needs its own resistor. Switching can take up to one second.