1863\. Sum of All Subset XOR Totals

Easy

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`.

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 = [1,3]

**Output:** 6

**Explanation:** The 4 subsets of [1,3] are: 

- The empty subset has an XOR total of 0. 

- [1] has an XOR total of 1. 

- [3] has an XOR total of 3. 

- [1,3] has an XOR total of 1 XOR 3 = 2. 
  
0 + 1 + 3 + 2 = 6

**Example 2:**

**Input:** nums = [5,1,6]

**Output:** 28

**Explanation:** The 8 subsets of [5,1,6] are: 

- The empty subset has an XOR total of 0. 

- [5] has an XOR total of 5.

- [1] has an XOR total of 1. 

- [6] has an XOR total of 6. 

- [5,1] has an XOR total of 5 XOR 1 = 4. 

- [5,6] has an XOR total of 5 XOR 6 = 3. 

- [1,6] has an XOR total of 1 XOR 6 = 7. 

- [5,1,6] has an XOR total of 5 XOR 1 XOR 6 = 2. 
  
0 + 5 + 1 + 6 + 4 + 3 + 7 + 2 = 28

**Example 3:**

**Input:** nums = [3,4,5,6,7,8]

**Output:** 480

**Explanation:** The sum of all XOR totals for every subset is 480.

**Constraints:**

*   `1 <= nums.length <= 12`
*   `1 <= nums[i] <= 20`