#643 - Maximum Average Subarray I

EasySliding Window

Given an integer array nums of length n and an integer k, find a contiguous subarray of length k that has the maximum average value, and return that average. The answer will be accepted if the error is less than 10⁻⁵.

Input	Output
nums = [1,12,-5,-6,50,3], k = 4	12.75
nums = [5], k = 1	5.0
nums = [0,4,0,3,2], k = 1	4.0

Solution Space

Try it

/**
 * Finds the maximum average of any contiguous subarray of length k.
 *
 * @param nums Array of integers
 * @param k Window size
 * @returns Maximum average value
 */
export function findMaxAverage(nums: number[], k: number): number {
  // Compute the sum of the first window
  let windowSum = 0;
  for (let i = 0; i < k; i++) windowSum += nums[i];

  let maxSum = windowSum;

  // Slide: add the incoming element, drop the outgoing element
  for (let i = k; i < nums.length; i++) {
    windowSum += nums[i] - nums[i - k];
    if (windowSum > maxSum) maxSum = windowSum;
  }

  return maxSum / k;
}

Approach: fixed-size sliding window – maintain a window of size k, updating the sum by adding the new element and subtracting the old element as the window slides.

Time: O(n) – one pass to build the initial window, one pass to slide it.

Space: O(1) – only a few numeric variables.

#1679 Max Number of K-Sum Pairs

#1004 Max Consecutive Ones III