Is Find Maximum Balanced XOR Subarray Length easy or hard?

The problem is generally categorized as Medium difficulty. The main challenge is recognizing the prefix XOR pattern and using a hash map to track previously seen XOR states to achieve an O(n) solution.

Find Maximum Balanced XOR Subarray Length Python/Java solution

Most implementations compute a running prefix XOR and store indices in a dictionary or map. Python typically uses a dictionary, Java uses HashMap, C++ uses unordered_map, and Go or TypeScript use their respective map structures. All versions follow the same O(n) prefix XOR logic.

How to solve Find Maximum Balanced XOR Subarray Length in O(n)?

Maintain a running prefix XOR while iterating through the array. Store the earliest index where each XOR value appears in a hash map. If the same XOR value appears again at index i, the subarray between the stored index and i has XOR equal to zero. Update the maximum length using this distance.

What is the best approach for Find Maximum Balanced XOR Subarray Length?

The best approach uses prefix XOR with a hash table. Track the cumulative XOR while iterating through the array and store the first index where each XOR value appears. When the same XOR appears again, the subarray between the two indices has XOR equal to zero. This method runs in O(n) time and O(n) space.

Is Find Maximum Balanced XOR Subarray Length asked at Google/Amazon/Meta?

Prefix XOR and longest zero-XOR subarray patterns appear in interviews at companies like Amazon, Google, and Meta. Variations of this problem test understanding of prefix techniques, hash maps, and bit manipulation in subarray problems.

What data structure is used in Find Maximum Balanced XOR Subarray Length?

A hash table (hash map) is used to store the first occurrence of each prefix XOR value. This allows constant-time lookups to determine whether the same XOR state has appeared before and compute the corresponding subarray length.

What is the time complexity of Find Maximum Balanced XOR Subarray Length?

The optimal solution runs in O(n) time because each element is processed once while maintaining a prefix XOR and performing constant‑time hash table lookups. The brute force method takes O(n^2) time since it evaluates every possible subarray.

Description Hints 2 Solution Video 19:30

3755. Find Maximum Balanced XOR Subarray Length

Medium50.8% acceptance

Given an integer array nums, return the length of the longest subarray that has a bitwise XOR of zero and contains an equal number of even and odd numbers. If no such subarray exists, return 0.

Example 1:

Input: nums = [3,1,3,2,0]

Output: 4

Explanation:

The subarray [1, 3, 2, 0] has bitwise XOR 1 XOR 3 XOR 2 XOR 0 = 0 and contains 2 even and 2 odd numbers.

Example 2:

Input: nums = [3,2,8,5,4,14,9,15]

Output: 8

Explanation:

The whole array has bitwise XOR 0 and contains 4 even and 4 odd numbers.

Example 3:

Input: nums = [0]

Output: 0

Explanation:

No non-empty subarray satisfies both conditions.

Constraints:

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

Topics

Hints open one at a time

Hint 1

In one pass maintain prefix pxor and prefix diff = (#evens − #odds) and record in a hash‑map the earliest index where each state (pxor,diff) occurs.

Hint 2

At each index, if the current state (pxor,diff) is already in the map, update the max length as the current index minus the recorded index.

19:30

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

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

[3,1,3,2,0]

Input

[3,2,8,5,4,14,9,15]

Input

[0]

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