Moving Average from Data Stream

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

For example,

MovingAverage m = new MovingAverage(3); m.next(1) = 1 m.next(10) = (1 + 10) / 2 m.next(3) = (1 + 10 + 3) / 3 m.next(5) = (10 + 3 + 5) / 3

Solution

public class MovingAverage {

    int count;
    double sum;
    int size;
    Queue<Integer> queue;

    public MovingAverage(int size) {
        count = 0;
        sum = 0;
        this.size = size;
        queue = new LinkedList<>();
    }

    public double next(int val) {
        if (queue.size() < size) {
            queue.add(val);
            sum += val;
            return sum / queue.size();
        } else {
            Integer remove = queue.remove();
            sum -= remove;

            queue.add(val);
            sum += val;
            return sum / queue.size();
        }
    }
}

/**
 * Your MovingAverage object will be instantiated and called as such:
 * MovingAverage obj = new MovingAverage(size);
 * double param_1 = obj.next(val);
 */