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

一刷
题解：首先要思考需要些什么变量
一个收尾相连的长度为size的数组，一个指向被替代位置的int, 一个当前数组含有多少个元素的int

class MovingAverage {
    int[] window;
    int insert, n;
    long sum;

    /** Initialize your data structure here. */
    public MovingAverage(int size) {
        window = new int[size];
        insert = 0;
        n = 0;
    }
    
    public double next(int val) {
        if(n<window.length){
            window[n++] = val;
            sum+=val;
        }else{
            sum -= window[insert];
            sum += val;
            window[insert] = val;
            insert++;
            insert = insert%window.length;
        }
        return (double)sum/n;
    }
}

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