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

class MovingAverage {
public:
    /** Initialize your data structure here. */
    MovingAverage(int size) {
        windowSize = size;
        count = 0;
        currentSum = 0;
    }
    
    double next(int val) {
        value.push_back(val);
        currentSum += val;
        count++;
        if (count > windowSize) {
            currentSum -= value[count - 1 - windowSize];
            return currentSum / windowSize;
        }
        return currentSum / count;
    }
private:
    int windowSize;
    int count;
    double currentSum;
    vector<int> value;
};

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