643. Maximum Average Subarray I

You are given an integer array nums consisting of n elements, and an integer k.

Find a contiguous subarray whose length is 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: Maximum average is (12 - 5 - 6 + 50) / 4 = 51 / 4 = 12.75

Example 2:

Input: nums = [5], k = 1 Output: 5.00000

Constraints:

n == nums.length
1 <= k <= n <= 105
-104 <= nums[i] <= 104
class Solution {
    public double findMaxAverage(int[] nums, int k) {
        int currentSum = 0;
        for (int i = 0; i < k; i++){
            currentSum += nums[i];
        }
        // int currentSum = Arrays.stream(nums).limit(k).sum();  slow
        double bigSum = currentSum;
        for (int i = k; i < nums.length; i++){
            currentSum += nums[i];
            currentSum -= nums[i - k];
            if (currentSum > bigSum){
                bigSum = currentSum;
            }
        }
        return bigSum / k;
        
    }
}