Sum of All Subsets XOR Total

The XOR total of an array is defined as the bitwise XOR of all its elements, or 0 if the array is empty.

• For example, the XOR total of the array [2,5,6] is 2 XOR 5 XOR 6 = 1.

You are given an array nums, return the sum of all XOR totals for every subset of nums.

Note: Subsets with the same elements should be counted multiple times.

An array a is a subset of an array b if a can be obtained from b by deleting some (possibly zero) elements of b.

Example 1:

Input: nums = [2,4]

Output: 12

Explanation: The four subsets of [2,4] are

1. The empty subset has an XOR total of 0.
2. [2] has an XOR total of 2.
3. [4] has an XOR total of 4.
4. [2,4] has an XOR total of (2 XOR 4 = 6).
   The sum of all XOR totals is 0 + 2 + 4 + 6 = 12.

Example 2:

Input: [3,1,1]

Output: 12

Explanation: The eight subsets of [3,1,1] are

1. The empty subset has an XOR total of 0.
2. [3] has an XOR total of 3.
3. [1] has an XOR total of 1.
4. [1] has an XOR total of 1.
5. [3,1] has an XOR total of (3 XOR 1 = 2).
6. [3,1] has an XOR total of (3 XOR 1 = 2).
7. [1,1] has an XOR total of (1 XOR 1 = 0).
8. [3,1,1] has an XOR total of (3 XOR 1 XOR 1 = 3).
   The sum of all XOR totals is 0 + 3 + 1 + 1 + 2 + 2 + 0 + 3 = 12.

Constraints:

• 1 <= nums.length <= 12
• 1 <= nums[i] <= 20