Minimum Impossible OR — LeetCode 2568 Python Solution

The problem

You are given a 0-indexed integer array nums. We say that an integer x is expressible from nums if there exist some integers 0 <= index1 < index2 < ...

Example

Input

nums = [2,1]

Output

4

Explanation

1 and 2 are already present in the array. We know that 3 is expressible, since nums[0] | nums[1] = 2 | 1 = 3. Since 4 is not expressible, we return 4.

Python solution

class Solution:
    def minImpossibleOR(self, nums: List[int]) -> int:
        s = set(nums)
        return next(1 << i for i in range(32) if 1 << i not in s)

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 2568. Minimum Impossible OR is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

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

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