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]
is2 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: 28

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
Solution:
class Solution {
/**
* @param Integer[] $nums
* @return Integer
*/
function subsetXORSum($nums) {
return array_reduce($nums, function($carry, $item) {
return $carry  $item;
}) << (count($nums)  1);
}
}
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