LeetCode-in-Java

3702. Longest Subsequence With Non-Zero Bitwise XOR

Medium

You are given an integer array nums.

Return the length of the longest subsequence in nums whose bitwise XOR is non-zero. If no such subsequence exists, return 0.

Example 1:

Input: nums = [1,2,3]

Output: 2

Explanation:

One longest subsequence is [2, 3]. The bitwise XOR is computed as 2 XOR 3 = 1, which is non-zero.

Example 2:

Input: nums = [2,3,4]

Output: 3

Explanation:

The longest subsequence is [2, 3, 4]. The bitwise XOR is computed as 2 XOR 3 XOR 4 = 5, which is non-zero.

Constraints:

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

Solution

public class Solution {
    public int longestSubsequence(int[] nums) {
        int xorSum = 0;
        boolean allZero = true;
        for (int num : nums) {
            xorSum ^= num;
            if (num != 0) {
                allZero = false;
            }
        }
        if (allZero) {
            return 0;
        }
        return xorSum != 0 ? nums.length : nums.length - 1;
    }
}

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