3513. Number of Unique XOR Triplets I

You are given an integer array nums of length n, where nums is a permutation of the numbers in the range [1, n].

A XOR triplet is defined as the XOR of three elements nums[i] XOR nums[j] XOR nums[k] where i <= j <= k.

Return the number of unique XOR triplet values from all possible triplets (i, j, k).

A permutation is a rearrangement of all the elements of a set.

class Solution {
public:
    int uniqueXorTriplets(vector<int>& nums) {
        int n = nums.size();
        return n <= 2 ? n : pow(2, 64 - __builtin_clzll(n));
    }
};