You are given an integer array nums consisting of n elements, and an integer k. Find a contiguous subarray whose length is greater than or equal to k that has the maximum average value and return this value. Any answer with a calculation error less than 10-5 will be accepted. Example 1: Input: nums = [1,12,-5,-6,50,3], k = 4 Output: 12.75000 Explanation: - When the length is 4, averages are [0.5, 12.75, 10.5] and the maximum average is 12.75 - When the length is 5, averages are [10.4, 10.8] and the maximum average is 10.8 - When the length is 6, averages are [9.16667] and the maximum average is 9.16667 The maximum average is when we choose a subarray of length 4 (i.e., the sub array [12, -5, -6, 50]) which has the max average 12.75, so we return 12.75 Note that we do not consider the subarrays of length < 4. Example 2: Input: nums = [5], k = 1 Output: 5.00000 Constraints: n == nums.length 1 <= k <= n <= 104 -104 <= nums[i] <= 104