Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.
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
数据流中的平均值。题意很简单，就是不断接受来自数据流的数字，算平均值。如果接收的数字的个数大于规定的size，则开始弹出队首元素。
时间O(n)
空间O(n)
Java实现
1 class MovingAverage { 2 private Queue<Integer> queue; 3 private double sum = 0; 4 private int size; 5 6 /** Initialize your data structure here. */ 7 public MovingAverage(int size) { 8 this.size = size; 9 queue = new LinkedList<>(); 10 } 11 12 public double next(int val) { 13 if (queue.size() == size) { 14 sum -= queue.poll(); 15 } 16 queue.offer(val); 17 sum += val; 18 return sum / queue.size(); 19 } 20 } 21 22 /** 23 * Your MovingAverage object will be instantiated and called as such: 24 * MovingAverage obj = new MovingAverage(size); 25 * double param_1 = obj.next(val); 26 */