LeetCode-in-Java

643. Maximum Average Subarray I

Easy

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:

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

Example 2:

Input: nums = [5], k = 1

Output: 5.00000

Constraints:

• n == nums.length
• 1 <= k <= n <= 105
• -104 <= nums[i] <= 104

Solution

public class Solution {
    public double findMaxAverage(int[] nums, int k) {
        double windowSum = 0;
        int windowStart = 0;
        double max = Integer.MIN_VALUE;
        for (int windowEnd = 0; windowEnd < nums.length; ++windowEnd) {
            windowSum += nums[windowEnd];
            if (windowEnd >= k - 1) {
                double candidate = windowSum / k;
                max = Math.max(candidate, max);
                windowSum -= nums[windowStart];
                windowStart++;
            }
        }
        return max;
    }
}

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