Find unique binary string

Array Hash Table String Backtracking

79.4% acceptance

Feb 25, 2026

2562

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.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn find_different_binary_string(nums: Vec<String>) -> String {
    // Cantor's diagonal argument: differ from nums[i] at position i
    nums.iter()
      .enumerate()
      .map(|(i, s)| {
        if s.as_bytes()[i] == b'0' { '1' } else { '0' }
      })
      .collect()
  }
}