剑指 Offer II 041. 滑动窗口的平均值

class MovingAverage {
public:
    int size;
    double sum=0.0;
    queue<int> window;
    /** Initialize your data structure here. */
    MovingAverage(int size) {
        this->size= size;
        this->sum = 0.0;
    }
    
    double next(int val) {
        if(window.size()==this->size){
            sum-=window.front();
            window.pop();
        }
        window.push(val);
        sum+=val;
        return sum/window.size();
    }
};