1980. Find Unique Binary String

https://leetcode.com/problems/find-unique-binary-string

Description

Given an array of strings nums containing n unique binary strings each of length n, return a binary string of length n that does not appear in nums. If there are multiple answers, you may return any of them.

Example 1:

**Input:** nums = ["01","10"]
**Output:** "11"
**Explanation:** "11" does not appear in nums. "00" would also be correct.

Example 2:

**Input:** nums = ["00","01"]
**Output:** "11"
**Explanation:** "11" does not appear in nums. "10" would also be correct.

Example 3:

**Input:** nums = ["111","011","001"]
**Output:** "101"
**Explanation:** "101" does not appear in nums. "000", "010", "100", and "110" would also be correct.

Constraints:

• n == nums.length

• 1 <= n <= 16

• nums[i].length == n

• nums[i] is either '0' or '1'.

• All the strings of nums are unique.

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