Leetcode 643 - Maximum Average Subarray I

Note:

  • Sliding window problem.
  • Learned how to write slidign window code elegantly.

Question:

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
2
3
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

Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
/**
* @param {number[]} nums
* @param {number} k
* @return {number}
*/
var findMaxAverage = function(nums, k) {
let max = -Infinity;
let sum = 0;
for (let i = 0; i < nums.length; i++) {
// Add cur to sum first.
sum += nums[i];
// When i = k - 1, the window is full.
// Check avg then delete the head so we'll have space for next elem.
if (i >= k - 1) {
max = Math.max(max, sum / k);
sum -= nums[i - k + 1];
}
}
return max;
};