LeetCode 346. 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);
 */