LeetCode 1695: Maximum Erasure Value (Sliding Window) ·

Table of Contents

Meta Data
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Difficulty: Medium First Attempt: 2025-08-09

Total time: 00:00.00

Intuition
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This is a classic sliding window with a uniqueness constraint. Maintain a window that contains no duplicates. Move the right pointer forward; while nums[right] is already in the window, shrink from the left by removing values and subtracting them from the running sum. Then insert nums[right], update the running sum, and track the maximum.

Approach
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class Solution:
    def maximumUniqueSubarray(self, nums: List[int]) -> int:
        left = max_score = score_now = 0
        occur = set()

        for right in range(len(nums)):
            while nums[right] in occur:
                occur.remove(nums[left])
                score_now -= nums[left]
                left += 1

            occur.add(nums[right])
            score_now += nums[right]
            max_score = max(max_score, score_now)

        return max_score

Complexity
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Time: O(n)
Space: O(n)

Findings
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Keeping a running sum avoids recomputing subarray sums when the window moves.
A set gives O(1) membership checks to enforce uniqueness.
This is a standard two-pointer pattern; the same template applies to many “longest/maximum subarray with constraint” problems.