643. Maximum Average Subarray I

Ref: https://leetcode-cn.com/problems/maximum-average-subarray-i/

这道题思路比较清晰，滑动窗口，维持窗口的sum，每次减去滑动前第一个元素，加上滑动后最后一个元素，代码实现如下：

class Solution:
   def findMaxAverage(self, nums: List[int], k: int) -> float:

       m_sum = sum(nums[:k])
       result = m_sum
       for i, j in zip(nums[:-k], nums[k:]):
           m_sum -= i
           m_sum += j
           if m_sum > result:
               result = m_sum
       return result / k