解决方法：滑动窗口方案
class Solution {
public:
double findMaxAverage(vector<int>& nums, int k) {
double r = INT_MIN;
double sum = 0;
for (int i = 0; i<nums.size(); i++) {
if (i<k) {
sum+=nums[i];
}else{
r = max(sum, r);
sum +=nums[i]-nums[i-k];
}
}
r = max(sum, r);
return r/double(k);
}
};
