three consecutive LEDs, turn on and off with button

int yellow_led = 13;
int green_led = 12;
int red_led = 11;
int button = 2;
int state = HIGH;
int prevstate = HIGH;


// the setup routine runs once when you press reset:
void setup() {
  // initialize the digital pin as an output.
  pinMode(yellow_led, OUTPUT);
  pinMode(green_led, OUTPUT);
  pinMode(red_led, OUTPUT);
  pinMode(button, INPUT);

}

// the loop routine runs over and over again forever:
void loop() {

    state = digitalRead(button);
    if(state != prevstate){
      while(state == HIGH){
          digitalWrite(yellow_led, HIGH);   // turn the LED on (HIGH is the voltage level)
          delay(300);
          digitalWrite(green_led, HIGH);
          delay(300);
          digitalWrite(red_led, HIGH);
          delay(300);
          digitalWrite(yellow_led, LOW);
          delay(300);
          digitalWrite(green_led, LOW);
          delay(300);
          digitalWrite(red_led, LOW);
          state = !digitalRead(button); //this code allows the program to work only if button is pressed right before red LED turns off
          delay(300);
          }
        }
    prevstate = state;
}