maxAvgSubarray1.js

/* 
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
*/

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
var findMaxAverage = function (nums, k) {
    let i = 1
    let sum = nums.slice(0, k).reduce((a, b) => a + b)
    let avg = sum / k

    while (i <= nums.length - k) {
        sum = sum - nums[i - 1] + nums[i + k - 1]
        const tempAvg = sum / k
        if (tempAvg > avg) {
            avg = tempAvg
        }
        i++
    }

    return avg
};