Traffic Lights

// traffic light LED

const int led[3] = {4, 5, 6};
const int button[3] = {10, 12, 11};

int state[3] = {0, 0, 0};
int button_on[3] = {0, 0, 0};
long last_time[3] = {0, 0, 0};
long cur_time[3] = {0, 0, 0};
long debounce_delay = 500;


void setup() {
  for (int i = 0; i < 3; i++) {
    pinMode(led[i], OUTPUT);
  }
  for (int i = 0; i < 3; i++) {
    pinMode(button[i], INPUT_PULLUP);
  }
}

void loop() {
  for (int i = 0; i < 3; i++) {
    digitalWrite(led[i], state[i]);
    button_on[i] = (digitalRead(button[i]) == LOW);
    cur_time[i] = millis();
    if (cur_time[i] - last_time[i] > debounce_delay) {
      if (button_on[i]) {
        state[i] = 1 - state[i];
        last_time[i] = cur_time[i];    
      }
    };
  };    
}