0346. Moving Average from Data Stream

https://leetcode.com/problems/moving-average-from-data-stream

Description

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

Constraints:

• 1 <= size <= 1000

• -105 <= val <= 105

• At most 104 calls will be made to next.

ac

class MovingAverage {
    private int size;
    private int sum;
    private Queue<Integer> q;

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

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

        return sum * 1.0 / q.size();
    }
}

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