LeetCode 1984: Minimum Difference Between Highest and Lowest of K Scores

Meta Data

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Difficulty: easy First Attempt: 2026-01-26

• Submissions: Accepted ×2

Approach

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After sorting, minimizing highest minus lowest means the k chosen scores are contiguous: if one in the middle were skipped, swapping it in for the highest or lowest could only shrink the difference or keep it.

A fixed window of length k has difference nums[right] - nums[right - k + 1].

My Solution

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class Solution:
    def minimumDifference(self, nums: List[int], k: int) -> int:
        nums.sort()
        return min(nums[i + k - 1] - nums[i] for i in range(len(nums) - k + 1))

My first accepted version maintained left by hand, plus an unused min_num; the second used right - k + 1 as the left end directly, which is much cleaner.

Complexity

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Time O(n log n), space O(1) apart from sorting.

Mistakes to Avoid

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• Looking for a contiguous block without sorting: any k scores may be chosen, not a contiguous run.

Interview Explanation

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After sorting, the best k scores are contiguous, since including a skipped value never widens the gap. So I sort and slide a window of length k, where the difference is the two ends subtracted, and take the minimum. Time O(n log n).