1863. Sum of All Subset XOR Totals

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# 題目敘述

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.
• [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.

# 解題思路

# Solution

class Solution {

    public int subsetXORSum(int[] nums) {

        int ans = 0;

        for(int num : nums) ans |= num;

        return ans << (nums.length - 1);

    }

}