const int buttonPin = 2;    // the number of the pushbutton pin
const int redPin = 9;       // the number of the red LED pin
const int greenPin = 10;    // the number of the green LED pin
const int bluePin = 11;     // the number of the blue LED pin

int buttonState = 0;        // variable for reading the pushbutton status
int lastButtonState = 0;    // variable to store the previous state of the button
int colorState = 0;         // variable for tracking the current color

void setup() {
  pinMode(buttonPin, INPUT);  // initialize the pushbutton pin as an input (with external pull-up resistor)
  pinMode(redPin, OUTPUT);    // initialize the red LED pin as an output
  pinMode(greenPin, OUTPUT);  // initialize the green LED pin as an output
  pinMode(bluePin, OUTPUT);   // initialize the blue LED pin as an output
  digitalWrite(redPin, LOW);  // start with all LEDs off
  digitalWrite(greenPin, LOW);
  digitalWrite(bluePin, LOW);
}

void loop() {
  buttonState = digitalRead(buttonPin);  // read the state of the pushbutton

  if (buttonState == LOW && lastButtonState == HIGH) {  // check if the pushbutton is pressed
    colorState++;  // increment color state
    if (colorState > 2) {  // wrap around color states
      colorState = 0;
    }
    changeColor(colorState);  // change the color of the LED
    delay(1000);  // delay for 500 milliseconds
  }
  lastButtonState = buttonState;  // update the last button state
}

void changeColor(int state) {
  switch (state) {
    case 0:
      setColor(255, 0, 0);  // Red
      break;
    case 1:
      setColor(0, 255, 0);  // Green
      break;
    case 2:
      setColor(0, 0, 255);  // Blue
      break;
  }
}

void setColor(int red, int green, int blue) {
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);
}