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

 1 class MovingAverage {
 2 public:
 3     /** Initialize your data structure here. */
 4     MovingAverage(int size) {
 5         windowSize = size;
 6         count = 0;
 7         currentSum = 0;
 8     }
 9     
10     double next(int val) {
11         value.push_back(val);
12         currentSum += val;
13         count++;
14         if (count > windowSize) {
15             currentSum -= value[count - 1 - windowSize];
16             return currentSum / windowSize;
17         }
18         return currentSum / count;
19     }
20 private:
21     int windowSize;
22     int count;
23     double currentSum;
24     vector<int> value;
25 };
26 
27 /**
28  * Your MovingAverage object will be instantiated and called as such:
29  * MovingAverage obj = new MovingAverage(size);
30  * double param_1 = obj.next(val);
31  */