[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.

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

数据流中的平均值。题意很简单，就是不断接受来自数据流的数字，算平均值。如果接收的数字的个数大于规定的size，则开始弹出队首元素。

时间O(n)

空间O(n)

Java实现

class MovingAverage {
    private Queue<Integer> queue;
    private double sum = 0;
    private int size;

    /** Initialize your data structure here. */
    public MovingAverage(int size) {
        this.size = size;
        queue = new LinkedList<>();
    }
    
    public double next(int val) {
        if (queue.size() == size) {
            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);
 */

LeetCode 题目总结