Is Minimum Subarray Length With Distinct Sum At Least K easy or hard?

This problem is generally considered Medium difficulty. The main challenge is correctly maintaining the distinct sum while handling duplicate values during window expansion and contraction. Once you recognize the sliding window pattern with frequency tracking, the implementation becomes straightforward.

Minimum Subarray Length With Distinct Sum At Least K Python/Java solution

Most implementations follow the same pattern across languages: maintain two pointers for the window, a hash map for frequencies, and a variable storing the sum of distinct elements. Python typically uses defaultdict or Counter, while Java uses HashMap. The algorithm runs in O(n) time in both languages.

How to solve Minimum Subarray Length With Distinct Sum At Least K in O(n)?

Use two pointers to maintain a sliding window and a hash map to track element frequencies. When a number appears for the first time in the window, add its value to the distinct sum. Once the distinct sum reaches or exceeds k, move the left pointer to shrink the window while updating frequencies and subtracting values when counts reach zero. Track the minimum window length during this process.

What is the best approach for Minimum Subarray Length With Distinct Sum At Least K?

The most efficient solution uses a sliding window combined with a hash map to track element frequencies. As the right pointer expands the window, the algorithm updates the sum of distinct values. When the distinct sum becomes at least k, the left pointer shrinks the window to find the minimum valid length. This approach runs in O(n) time with O(n) space.

Is Minimum Subarray Length With Distinct Sum At Least K asked at Google/Amazon/Meta?

Problems combining sliding window and hash map frequency tracking commonly appear in interviews at companies like Amazon, Google, and Meta. Variants involving minimum window size, distinct elements, or target sums are frequent in coding interviews because they test two-pointer optimization and data structure usage.

What data structure is used in Minimum Subarray Length With Distinct Sum At Least K?

The key data structure is a hash table (hash map) that stores the frequency of each element inside the current window. This allows the algorithm to quickly determine when an element becomes newly distinct or when it should be removed from the distinct sum during window contraction.

What is the time complexity of Minimum Subarray Length With Distinct Sum At Least K?

The optimal sliding window solution runs in O(n) time because each element is added to and removed from the window at most once. Hash map updates and lookups occur in constant time. Space complexity is O(n) in the worst case when all elements in the window are unique.

Description Hints 3 Solution Video 13:52

3795. Minimum Subarray Length With Distinct Sum At Least K

Medium31.7% acceptance1 company

You are given an integer array nums and an integer k.

Return the minimum length of a subarray whose sum of the distinct values present in that subarray (each value counted once) is at least k. If no such subarray exists, return -1.

Example 1:

Input: nums = [2,2,3,1], k = 4

Output: 2

Explanation:

The subarray [2, 3] has distinct elements {2, 3} whose sum is 2 + 3 = 5, which is at least k = 4. Thus, the answer is 2.

Example 2:

Input: nums = [3,2,3,4], k = 5

Output: 2

Explanation:

The subarray [3, 2] has distinct elements {3, 2} whose sum is 3 + 2 = 5, which is at least k = 5. Thus, the answer is 2.

Example 3:

Input: nums = [5,5,4], k = 5

Output: 1

Explanation:

The subarray [5] has distinct elements {5} whose sum is 5, which is at least k = 5. Thus, the answer is 1.

Constraints:

1 <= nums.length <= 10⁵
1 <= nums[i] <= 10⁵
1 <= k <= 10⁹

Asked at 1 company

Amazon

Topics

Hints open one at a time

Hint 1

Use a two-pointer sliding window that expands the right end until the window's sum of values that occur exactly once reaches at least k.

Hint 2

When that happens, greedily advance the left pointer to shrink the window as much as possible while keeping the unique-sum >= k, updating the minimum length.

Hint 3

Maintain a frequency counter to update the unique-sum when an element's count flips between unique and non-unique

13:52

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1class Solution:
2    def minLength(self, nums: List[int], k: int) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

[2,2,3,1]
4

Input

[3,2,3,4]
5

Input

[5,5,4]
5

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