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:
<li>1 <= <code>k</code> <= <code>n</code> <= 30,000.</li>
<li>Elements of the given array will be in the range [-10,000, 10,000].</li>