643.子数组最大平均数I

方法一： 

class Solution {
public:
	double findMaxAverage(vector<int>& nums, int k) {
		double avg = 0,sum=0;
		for (int i = 0; i < k; i++)
			sum += nums[i];
		avg = sum / k;
		for (int i = k; i < nums.size(); i++)
		{
			sum = sum + nums[i] - nums[i - k];
			avg = max(sum/k, avg);
            cout<<avg<<endl;
		}
		return avg;
	}
};