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 {
    public double findMaxAverage(int[] nums, int k) {
        int count = 0;
        int window = 0;
        for(int i = 0; i < nums.length; i++) {
            if(i < k) {
                count += nums[i];
                window += nums[i];
            }
            else {
                window = window - nums[i - k] + nums[i];
                count = Math.max(count, window);
            }
        }
        return (double)count / k;
    }
}