Is Make the XOR of All Segments Equal to Zero easy or hard?

Make the XOR of All Segments Equal to Zero is classified as a Hard problem on LeetCode with an acceptance rate around 41%. The difficulty comes from recognizing the repeating index groups and applying dynamic programming over XOR states rather than attempting brute force segment checks.

Make the XOR of All Segments Equal to Zero Python/Java solution

Implement the DP approach by grouping indices with i % k, counting frequencies, and iterating through 1024 XOR states while updating minimal costs. Python solutions typically use lists for DP and dictionaries or arrays for counts, while Java implementations often use int arrays for both DP states and frequency tracking.

How to solve Make the XOR of All Segments Equal to Zero in O(n)?

A near linear approach groups elements by index modulo k and performs dynamic programming over 1024 XOR states. Frequency counts allow computing modification costs quickly for each candidate value. Because the number of XOR states is constant (1024), the overall complexity becomes O(n + k * 1024), which is effectively linear for typical constraints.

What is the best approach for Make the XOR of All Segments Equal to Zero?

The optimal solution uses dynamic programming with XOR state transitions. Split the array into k groups based on index modulo k, compute value frequencies per group, and maintain a DP array of 1024 XOR states. Each transition represents choosing a value for a group and paying the cost of modifying elements. This runs in O(n + k * 1024) time with O(1024) space.

Is Make the XOR of All Segments Equal to Zero asked at Google/Amazon/Meta?

Problems involving XOR properties, DP state compression, and grouping by modular indices are common in interviews at companies like Google, Amazon, and Meta. This specific LeetCode problem is considered hard and tests understanding of bit manipulation combined with dynamic programming optimization.

What data structure is used in Make the XOR of All Segments Equal to Zero?

The solution relies on frequency arrays or hash maps to count values within each modulo group, along with a dynamic programming array of size 1024 representing XOR states. These structures enable fast transitions when evaluating the cost of assigning values to groups.

What is the time complexity of Make the XOR of All Segments Equal to Zero?

The optimized dynamic programming solution runs in O(n + k * 1024) time. Building frequency tables for the k groups takes O(n), and each group updates up to 1024 XOR states. Space complexity is O(1024) for the DP array that tracks minimum modification cost for each XOR value.

Description Hints 2 Solution Video 35:25

1787. Make the XOR of All Segments Equal to Zero

Hard41.1% acceptance2 companies

You are given an array nums and an integer k. The XOR of a segment [left, right] where left <= right is the XOR of all the elements with indices between left and right, inclusive: nums[left] XOR nums[left+1] XOR ... XOR nums[right].

Return the minimum number of elements to change in the array such that the XOR of all segments of size k is equal to zero.

Example 1:

Input: nums = [1,2,0,3,0], k = 1
Output: 3
Explanation: Modify the array from [1,2,0,3,0] to from [0,0,0,0,0].

Example 2:

Input: nums = [3,4,5,2,1,7,3,4,7], k = 3
Output: 3
Explanation: Modify the array from [3,4,5,2,1,7,3,4,7] to [3,4,7,3,4,7,3,4,7].

Example 3:

Input: nums = [1,2,4,1,2,5,1,2,6], k = 3
Output: 3
Explanation: Modify the array from [1,2,4,1,2,5,1,2,6] to [1,2,3,1,2,3,1,2,3].

Constraints:

1 <= k <= nums.length <= 2000
0 <= nums[i] < 2¹⁰

Asked at 2 companies

Medianet

Google

Topics

Hints open one at a time

Hint 1

Let's note that for the XOR of all segments with size K to be equal to zeros, nums[i] has to be equal to nums[i+k]

Hint 2

Basically, we need to make the first K elements have XOR = 0 and then modify them.

35:25

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