LeetCode-in-Java
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: 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 <= 121 <= nums[i] <= 20
Solution
public class Solution {
public int subsetXORSum(int[] nums) {
if (nums.length == 0) {
return 0;
}
return subsetXORSum(nums, 0, 0);
}
private int subsetXORSum(int[] nums, int currIndex, int res) {
if (currIndex == nums.length) {
return res;
}
int sum1 = subsetXORSum(nums, currIndex + 1, nums[currIndex] ^ res);
int sum2 = subsetXORSum(nums, currIndex + 1, res);
return sum1 + sum2;
}
}