Description
You are given an array nums of non-negative integers and an integer k.
An array is called special if the bitwise OR of all of its elements is at least k.
Return the length of the shortest special non-empty subarray of nums, or return -1 if no special subarray exists.
Example 1:
Input: nums = [1,2,3], k = 2
Output: 1
Explanation:
The subarray [3] has OR value of 3. Hence, we return 1.
Example 2:
Input: nums = [2,1,8], k = 10
Output: 3
Explanation:
The subarray [2,1,8] has OR value of 11. Hence, we return 3.
Example 3:
Input: nums = [1,2], k = 0
Output: 1
Explanation:
The subarray [1] has OR value of 1. Hence, we return 1.
Constraints:
1 <= nums.length <= 2 * 1050 <= nums[i] <= 1090 <= k <= 109
Solution
Python3
class Solution:
def minimumSubarrayLength(self, nums: List[int], k: int) -> int:
N = len(nums)
res = inf
count = [0] * 32
curr = 0
def inc(x):
nonlocal curr, count
for p in range(32):
if x & (1 << p):
if count[p] == 0:
curr += 1 << p
count[p] += 1
def dec(x):
nonlocal curr, count
for p in range(32):
if x & (1 << p):
count[p] -= 1
if count[p] == 0:
curr -= 1 << p
i = 0
for j, x in enumerate(nums):
inc(x)
while i <= j and curr >= k:
res = min(res, j - i + 1)
dec(nums[i])
i += 1
if res == inf: return -1
return res