643. Maximum Average Subarray I

Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value. And you need to output the maximum average value.

Example 1:

Input: [1,12,-5,-6,50,3], k = 4
Output: 12.75
Explanation: Maximum average is (12-5-6+50)/4 = 51/4 = 12.75

Note:

1. 1 <= k <= n <= 30,000.
2. Elements of the given array will be in the range [-10,000, 10,000].

class Solution(object):
    def findMaxAverage(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: float
        """
        sum = 0
        current = 0
        n = 0
        for i in range(len(nums)):
            if n<k:
                current += nums[i]
                sum = current
                n += 1
            else:
                current = current - nums[i-k] + nums[i]
                sum = max(sum,current)
        return sum*1.0/k

so easy