Maximum Average Subarray I

Try It Yourself

Use the editor below to find the best average among all contiguous windows of exactly k values. Reuse the current window sum instead of adding every window again.

Submit your implementation when it passes the examples. Initialize the maximum from a real window so arrays containing negative values work correctly.

Solution

Sum the first k values to create the initial window. For every later position, add the value entering on the right and subtract the value leaving on the left.

Track the greatest window sum and divide it by k once at the end.

function findMaxAverage(nums, k) {
  let windowSum = 0;

  for (let index = 0; index < k; index++) {
    windowSum += nums[index];
  }

  let maximumSum = windowSum;

  for (let right = k; right < nums.length; right++) {
    windowSum += nums[right] - nums[right - k];
    maximumSum = Math.max(maximumSum, windowSum);
  }

  return maximumSum / k;
}

Big O notation