346. Moving Average from Data Stream

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LeetCode

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Problem

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

Implement the MovingAverage class:

MovingAverage(int size) Initializes the object with the size of the window size. double next(int val) Returns the moving average of the last size values of the stream.

Example 1:

Input
["MovingAverage", "next", "next", "next", "next"]
[[3], [1], [10], [3], [5]]
Output
[null, 1.0, 5.5, 4.66667, 6.0]

Explanation
MovingAverage movingAverage = new MovingAverage(3);
movingAverage.next(1); // return 1.0 = 1 / 1
movingAverage.next(10); // return 5.5 = (1 + 10) / 2
movingAverage.next(3); // return 4.66667 = (1 + 10 + 3) / 3
movingAverage.next(5); // return 6.0 = (10 + 3 + 5) / 3

Code

class MovingAverage {
    int size;
    Queue<Integer> queue;
    double sum;
    public MovingAverage(int size) {
        this.size = size;
        this.sum = 0;
        this.queue = new LinkedList<>();
    }

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

        return sum / this.queue.size();
    }
}