Hard
You are given an integer array nums
of length n
where each element is a non-negative integer.
Select two subsequences of nums
(they may be empty and are allowed to overlap), each preserving the original order of elements, and let:
X
be the bitwise XOR of all elements in the first subsequence.Y
be the bitwise XOR of all elements in the second subsequence.Return the maximum possible value of X XOR Y
.
Note: The XOR of an empty subsequence is 0.
Example 1:
Input: nums = [1,2,3]
Output: 3
Explanation:
Choose subsequences:
[2]
, whose XOR is 2.[2,3]
, whose XOR is 1.Then, XOR of both subsequences = 2 XOR 1 = 3
.
This is the maximum XOR value achievable from any two subsequences.
Example 2:
Input: nums = [5,2]
Output: 7
Explanation:
Choose subsequences:
[5]
, whose XOR is 5.[2]
, whose XOR is 2.Then, XOR of both subsequences = 5 XOR 2 = 7
.
This is the maximum XOR value achievable from any two subsequences.
Constraints:
2 <= nums.length <= 105
0 <= nums[i] <= 109
public class Solution {
public int maxXorSubsequences(int[] nums) {
int n = nums.length;
if (n == 0) {
return 0;
}
int x = 0;
while (true) {
int y = 0;
for (int v : nums) {
if (v > y) {
y = v;
}
}
if (y == 0) {
return x;
}
x = Math.max(x, x ^ y);
for (int i = 0; i < n; i++) {
int v = nums[i];
nums[i] = Math.min(v, v ^ y);
}
}
}
}