Sliding Window - Maximum Erasure Value

Given an array nums of positive integers, find the maximum sum of a subarray with all unique elements.

Input: [4,2,4,5,6] → Output: 17 (subarray [2,4,5,6])

Input: [5,2,1,2,5,2,1,2,5] → Output: 8 (subarray [5,2,1])

Sliding window with a HashSet to track unique elements in current window. When a duplicate is found, shrink the window from the left.

Maintain left pointer, running sum, and a HashSet of current window elements.
Expand right: if nums[right] already in set, remove nums[left] and advance left (repeat).
Add nums[right] to set and sum.
Track maximum sum.

import java.util.*; class Solution { public int maximumUniqueSubarray(int[] nums) { Set<Integer> seen = new HashSet<>(); int left = 0, sum = 0, max = 0; for (int right = 0; right < nums.length; right++) { while (seen.contains(nums[right])) { seen.remove(nums[left]); sum -= nums[left++]; } seen.add(nums[right]); sum += nums[right]; max = Math.max(max, sum); } return max; } }

Time Complexity: O(N)
Space Complexity: O(N) — HashSet