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Tested Python solution for LeetCode 898 with 19 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 898 # by problem number
lcpy gen -s bitwise_ors_of_subarrays # by problem name
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. The bitwise OR of a subarray of one integer is that integer.
A subarray is a contiguous non-empty sequence of elements within an array.
Input: arr = [0]
Output: 1
Explanation: There is only one possible result: 0.
Input: arr = [1,1,2]
Output: 3
Explanation: The possible subarrays are [1], [1], [2], [1, 1], [1, 2], [1, 1, 2].
These yield the results 1, 1, 2, 1, 3, 3.
There are 3 unique values, so the answer is 3.
Input: arr = [1,2,4]
Output: 6
Explanation: The possible results are 1, 2, 3, 4, 6, and 7.
1 <= arr.length <= 5 * 10^40 <= arr[i] <= 10^9class Solution:
# Time: O(n * 30) - each OR set only holds distinct prefix-OR values, at most 30 bits
# Space: O(30 * n) worst case across the rolling and global sets
def subarray_bitwise_ors(self, arr: list[int]) -> int:
seen: set[int] = set()
current: set[int] = set()
for num in arr:
current = {num | prev for prev in current} | {num}
seen |= current
return len(seen)
| Time | Space |
|---|---|
| O(n * 30) - each OR set only holds distinct prefix-OR values, at most 30 bits | O(30 * n) worst case across the rolling and global sets |