Leetcode: 346. 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:
Use a Queue serve as a sliding window, and also maintain the current sum inside of the window. 

Code (Java):

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

public class MovingAverage {     Queue<Integer> queue;     int n;     int sum;           /** Initialize your data structure here. */     public MovingAverage(int size) {         queue = new LinkedList<>();         n = size;         sum = 0;     }           public double next(int val) {         queue.offer(val);         double result = 0;         sum += val;         if (queue.size() <= n) {             result = (double) sum / queue.size();         } else {             int remove = queue.poll();             sum -= remove;             result = (double) sum / n;         }                   return result;     } }   /**  * Your MovingAverage object will be instantiated and called as such:  * MovingAverage obj = new MovingAverage(size);  * double param_1 = obj.next(val);  */