README.md

2568. Minimum Impossible OR

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 < ... < indexk < nums.length for which nums[index1] | nums[index2] | ... | nums[indexk] = x. In other words, an integer is expressible if it can be written as the bitwise OR of some subsequence of nums.

Return the minimum positive non-zero integer that is not expressible from nums.

Example 1:

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.

Example 2:

Input: nums = [5,3,2]
Output: 1
Explanation: We can show that 1 is the smallest number that is not expressible.

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109

Solutions (Rust)

1. Solution

use std::collections::HashSet;

impl Solution {
    pub fn min_impossible_or(nums: Vec<i32>) -> i32 {
        let nums = nums.into_iter().collect::<HashSet<_>>();

        for i in 0..32 {
            if !nums.contains(&(1 << i)) {
                return 1 << i;
            }
        }

        unreachable!()
    }
}