How hard is LeetCode 898. Bitwise ORs of Subarrays?

LeetCode 898. Bitwise ORs of Subarrays is rated Medium on LeetCode.

What is the time complexity of LeetCode 898. Bitwise ORs of Subarrays?

The Python solution on this page runs in O(n \times \log M).

What is the space complexity of LeetCode 898. Bitwise ORs of Subarrays?

The Python solution on this page uses O(n \times \log M) auxiliary space.

What topics does LeetCode 898. Bitwise ORs of Subarrays cover?

LeetCode 898. Bitwise ORs of Subarrays is tagged Bit Manipulation, Array and Dynamic Programming on LeetCode.

Bitwise ORs of Subarrays — LeetCode 898 Python Solution

MediumBit ManipulationArrayDynamic Programming

Problem: #898
Pattern: Bit Manipulation
Reading time: 2 min
Source: leetcode.com

The problem

Given an integer array arr, return the number of distinct bitwise ORs of all the non-empty subarrays of arr. The bitwise OR of a subarray is the bitwise OR of each integer in the subarray.

Example

Input: arr = [0]
Output: 1
Explanation: There is only one possible result: 0.

Python solution

Python

class Solution:
    def subarrayBitwiseORs(self, arr: List[int]) -> int:
        ans = set()
        s = set()
        for x in arr:
            s = {x | y for y in s} | {x}
            ans |= s
        return len(ans)

Complexity

Measure	Complexity
Time	O(n \times \log M)
Space	O(n \times \log M) auxiliary

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 898. Bitwise ORs of Subarrays is filed here because LeetCode tags it Bit Manipulation, which is the vocabulary this hub collects.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 898. Bitwise ORs of Subarrays?: LeetCode 898. Bitwise ORs of Subarrays is rated Medium on LeetCode.
What is the time complexity of LeetCode 898. Bitwise ORs of Subarrays?: The Python solution on this page runs in O(n \times \log M).
What is the space complexity of LeetCode 898. Bitwise ORs of Subarrays?: The Python solution on this page uses O(n \times \log M) auxiliary space.
What topics does LeetCode 898. Bitwise ORs of Subarrays cover?: LeetCode 898. Bitwise ORs of Subarrays is tagged Bit Manipulation, Array and Dynamic Programming on LeetCode.