leetcode 346. Moving Average from Data Stream

题目

这是一道locked题目
这是一道esay题，主要使用一个data(queue<int>)保存数据 和 sum(int)记录当前queue中元素之和。调用next函数的时候需要保证queue的大小为size，所以queue满的时候pop front，同时sum要减去即将被pop出的元素的值。然后push新的元素到queue，更新sum的值。返回值只需 sum / data/size(), 但要把sum和size都强制类型转换为double. That's it!

class MovingAverage {
public:
    /** Initialize your data structure here. */
    MovingAverage(int size) {
        this->size = size;
        sum = 0;
    ｝
    double next(int val) {
        if (data.size() == size) {
            sum -= data.front();
            data.pop();
        }
        data.push(val);
        sum += val;
        return (double)sum / (double)data.size();
    }
private:
    int sum;
    int size = 0;
    queue<int> data;
};

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