leetcode 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].
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   class Solution(object):     def findMaxAverage(self, nums, k):         """         :type nums: List[int]         :type k: int         :rtype: float         """         # just iterate         # init: s         s = sum(nums[:k])         ans = float(s)/k         for i in xrange(k, len(nums)):             s = s+nums[i]-nums[i-k]             ans = max(ans, float(s)/k)         return ans