// set pin numbers
const byte led1 = 12; // first led is pin 13
const byte led2 = 11; // second led is pin 12
const byte led3 = 10; // third led is pin 11
const byte BUTTON = 2; // pushbutton is pin 8
// variables
unsigned long ledstate = -1; // current state of output pin
byte currentButton;
byte lastButton = LOW;
int  reading;

boolean debounce(boolean last)
{
  boolean current = digitalRead(BUTTON); 	//Read the button state
  if (last != current) 					//if it's different…
  {
    delay(5); 						//wait 5ms
    current = digitalRead(BUTTON); 			//read it again
  }
  return current; 					//return the current value
}

void setup()
{
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(BUTTON, INPUT);

  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
}
void loop()
{
  currentButton = debounce(lastButton); 			//read deboucned state
  if (lastButton == LOW && currentButton == HIGH) 	//if it was pressed...
  {
    ledstate ++;
      if (ledstate == 3){
        ledstate = 0;
      }
    if (ledstate == 0){
        digitalWrite(led1, HIGH);
        }
        else digitalWrite(led1, LOW);
        
        if (ledstate == 1){
        digitalWrite(led2, HIGH);
        }
        else digitalWrite(led2, LOW);
        
        if (ledstate == 2){
        digitalWrite(led3, HIGH);
        }
        else digitalWrite(led3, LOW);
  }
  lastButton = currentButton; 				//reset button value
}