643. Maximum Average Subarray I

Easy · solved 2026-09-24 · Open on LeetCode

sliding-windowarray

Time O(n) · Space O(n)

Slicing off the first k elements and zipping the result with the original lines up every element with the one k places ahead. Those are exactly the element leaving the window and the element entering it.

class Solution:
    def findMaxAverage(self, nums: List[int], k: int) -> float:
        window = best = sum(nums[:k])
        for leaving, entering in zip(nums, nums[k:]):
            window += entering - leaving
            best = max(best, window)
        return best / k