MaximumAverageSubarray_I.js

// Source : https://leetcode.com/problems/maximum-average-subarray-i
// Author : Dean Shi
// Date   : 2017-07-15

/***************************************************************************************
 *
 * 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].
 *
 *
 ***************************************************************************************/

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
var findMaxAverage = function(nums, k) {
    let sum = 0, max

    for (let i = 0; i < k; ++i) {
        sum += nums[i]
    }
    max = sum

    for (let i = k; i < nums.length; ++i) {
        sum += nums[i] - nums[i - k]
        max = Math.max(max, sum)
    }
    return max / k
};