Special binary string

String Divide and Conquer Sorting

79.3% acceptance

Feb 21, 2026

1147

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Special binary strings are binary strings with the following two properties: The number of 0's is equal to the number of 1's. Every prefix of the binary string has at least as many 1's as 0's. You are given a special binary string s. A move consists of choosing two consecutive, non-empty, special substrings of s, and swapping them. Two strings are consecutive if the last character of the first string is exactly one index before the first character of the second string. Return the lexicographically largest resulting string possible after applying the mentioned operations on the string.

Solution

Rust

Time O(n log n)

Space O(n)

LeetCode

solution.rs

/*
 * Special binary strings are binary strings with the following two properties:
 * The number of 0's is equal to the number of 1's.
 * Every prefix of the binary string has at least as many 1's as 0's.
 * You are given a special binary string s.
 * A move consists of choosing two consecutive, non-empty, special substrings of s, and swapping them. Two strings are consecutive if the last character of the first string is exactly one index before the first character of the second string.
 * Return the lexicographically largest resulting string possible after applying the mentioned operations on the string.
 * Example 1:
 * Input: s = "11011000"
 * Output: "11100100"
 * Explanation: The strings "10" [occuring at s[1]] and "1100" [at s[3]] are swapped.
 * This is the lexicographically largest string possible after some number of swaps.
 * Example 2:
 * Input: s = "10"
 * Output: "10"
 * Constraints:
 * 1 <= s.length <= 50
 * s[i] is either '0' or '1'.
 * s is a special binary string.
 */
impl Solution {
  pub fn make_largest_special(s: String) -> String {
    let bytes = s.as_bytes();
    let mut segs: Vec<String> = vec![];
    let mut count = 0i32;
    let mut start = 0;
    for i in 0..bytes.len() {
      if bytes[i] == b'1' { count += 1; } else { count -= 1; }
      if count == 0 {
        let inner = Solution::make_largest_special(s[start+1..i].to_string());
        segs.push(format!("1{}0", inner));
        start = i + 1;
      }
    }
    segs.sort_by(|a, b| b.cmp(a));
    segs.join("")
  }
}