Is Final Element After Subarray Deletions easy or hard?

The problem is rated Medium because the operations appear complex at first. Once the XOR invariant is recognized, the implementation becomes straightforward with a single O(n) pass.

Final Element After Subarray Deletions Python/Java solution

The implementation is identical across languages: iterate through the array and XOR each element into an accumulator variable. Python, Java, C++, Go, and TypeScript all support the XOR operator, making the solution concise and efficient.

How to solve Final Element After Subarray Deletions in O(n)?

Iterate through the array and maintain a variable called result. For each element perform result ^= nums[i]. After processing all elements, result contains the value that must remain after any sequence of valid subarray deletions. The algorithm uses one linear pass and constant extra space.

What is the best approach for Final Element After Subarray Deletions?

The optimal approach uses a mathematical invariant: the final element equals the XOR of all numbers in the array. Subarray deletions effectively collapse segments, and because XOR is associative and commutative, the final value is independent of deletion order. A single pass computing the cumulative XOR solves the problem in O(n) time and O(1) space.

Is Final Element After Subarray Deletions asked at Google/Amazon/Meta?

Problems based on XOR invariants and array reduction frequently appear in interviews at companies like Google, Amazon, and Meta. Even if the exact question is different, recognizing associative operations and invariants is a common interview pattern.

What data structure is used in Final Element After Subarray Deletions?

The solution primarily uses a simple array traversal with a running XOR accumulator. No additional data structures such as stacks or hash maps are required, which keeps the space complexity constant.

What is the time complexity of Final Element After Subarray Deletions?

The optimal brain‑teaser solution runs in O(n) time because you scan the array once and compute a running XOR. Only a constant amount of extra memory is required, giving O(1) space complexity.

3828. Final Element After Subarray Deletions - Practice Online

You are given an integer array nums.

Two players, Alice and Bob, play a game in turns, with Alice playing first.

In each turn, the current player chooses any subarray nums[l..r] such that r - l + 1 < m, where m is the current length of the array.
The selected subarray is removed, and the remaining elements are concatenated to form the new array.
The game continues until only one element remains.

Alice aims to maximize the final element, while Bob aims to minimize it. Assuming both play optimally, return the value of the final remaining element.

Example 1:

Input: nums = [1,5,2]

Output: 2

Explanation:

One valid optimal strategy:

Alice removes [1], array becomes [5, 2].
Bob removes [5], array becomes [2]. Thus, the answer is 2.

Example 2:

Input: nums = [3,7]

Output: 7

Explanation:

Alice removes [3], leaving the array [7]. Since Bob cannot play a turn now, the answer is 7.

Constraints:

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