[LeetCode] 346. Moving Average from Data Stream

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

Thought process:
Use queue.

Solution:

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class MovingAverage {
    private double sum;
    private int capacity;
    private Queue<Integer> queue;

    /** Initialize your data structure here. */
    public MovingAverage(int size) {
        capacity = size;
        sum = 0;
        queue = new LinkedList<>();
    }
    
    public double next(int val) {
        if (queue.size() == capacity) {
            sum -= queue.poll();
        }
        queue.offer(val);
        sum += val;
        return sum / queue.size();
    }
}

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

Time complexity:

  • Constructor: O(1).
  • next(): O(1).
Location: Philadelphia, PA, USA

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