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

Question

difficulty: low
adj diff: 2

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.

Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
class MovingAverage {

	List<Integer> windowArray;
	int numCount;
	int windowSize;
	double totalSum;

	public MovingAverage(int size) {
		windowArray = new LinkedList<Integer>();
		windowSize = size;
		numCount = 0;
		totalSum = 0.0;
	}

	public double next(int val) {
		if (numCount == windowSize) {
			totalSum -= windowArray.remove(0);
			numCount--;
		}
		totalSum += val;
		windowArray.add(val);
		numCount++;

		return totalSum / numCount;
	}
}

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