Google – Moving Window

Google – Moving Window
给一个Iterator和一个window size, 要求Wrap这个iterator来实现一个moving window class，在call next()的时候返回moving average。
[Solution]
Queue
这题就不需要考虑Iterator的那些Edge case。

class MovingWindow implements Iterator<Double> {

   

  Iterator<Double> it;

  int window;

  Queue<Double> queue;

  double sum;

   

  public MovingWindow(Iterator<Double> it, int window) {

    this.it = it;

    this.window = window;

    this.queue = new LinkedList<>();

  }

   

  @Override

  public boolean hasNext() {

    return it.hasNext();

  }

   

  @Override

  public double next() {

    double curr = it.next();

    queue.offer(curr);

    sum += curr;

    if (queue.size() > window) {

      sum -= queue.poll();

    }

    return sum / window;

  }

}

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