LeetCode Moving Average from Data Stream

原题链接在这里：https://leetcode.com/problems/moving-average-from-data-stream/

题目：

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

题解：

维护一个queue, 当queue的size已经等于size时若是继续加新的val就需要poll值.

Time Complexity: MovingAverage(size) O(1), next(val) O(1).

Space: O(size) 需要维护queue

AC Java:

 public class MovingAverage {

     private LinkedList<Integer> que;
     private int size;
     private int sum;

     /** Initialize your data structure here. */
     public MovingAverage(int size) {
         this.que = new LinkedList<Integer>();
         this.size = size;
         this.sum = 0;
     }

     public double next(int val) {
         if(que.size() == this.size){
             this.sum -= que.poll();
         }
         que.offer(val);
         sum += val;
         return (double)this.sum/que.size();
     }
 }

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