Leetcode - 379 telephone directory management system (Design)

deque

class PhoneDirectory {
    
    private Deque<Integer> deque;
    public PhoneDirectory(int maxNumbers) {
    
         deque = new LinkedList<>();
         for(int i = 0; i < maxNumbers;i++)
            deque.offerLast(i);
    }
    
    public int get(){
    
        if(deque.size()!=0)
          return deque.pollFirst();
        else
          return -1;
    }
    public boolean check(int number) {
    
       return deque.contains(number);
    }
    
    public void release(int number) {
    
        if(!deque.contains(number))
            deque.offerLast(number);
    }
}

/** * Your PhoneDirectory object will be instantiated and called as such: * PhoneDirectory obj = new PhoneDirectory(maxNumbers); * int param_1 = obj.get(); * boolean param_2 = obj.check(number); * obj.release(number); */