- Difficulty: Medium
- Tags: LeetCode, Medium, Bit Manipulation, Array, Backtracking, Enumeration, leetcode-2044, Dynamic Programming, O(min(2^n, m * n)), O(min(2^n, m)), DP
Problem
Given an integer array nums
, find the maximum possible bitwise OR of a subset of nums
and return the number of different non-empty subsets with the maximum bitwise OR.
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
. Two subsets are considered different if the indices of the elements chosen are different.
The bitwise OR of an array a
is equal to a[0] OR a[1] OR ... OR a[a.length - 1]
(0-indexed).
Example 1:
Input: nums = [3,1] Output: 2 Explanation: The maximum possible bitwise OR of a subset is 3. There are 2 subsets with a bitwise OR of 3: - [3] - [3,1]
Example 2:
Input: nums = [2,2,2] Output: 7 Explanation: All non-empty subsets of [2,2,2] have a bitwise OR of 2. There are 23 - 1 = 7 total subsets.
Example 3:
Input: nums = [3,2,1,5] Output: 6 Explanation: The maximum possible bitwise OR of a subset is 7. There are 6 subsets with a bitwise OR of 7: - [3,5] - [3,1,5] - [3,2,5] - [3,2,1,5] - [2,5] - [2,1,5]
Constraints:
1 <= nums.length <= 16
1 <= nums[i] <= 105