Better compression of string

Hash Table String Sorting Counting

75.3% acceptance

Mar 31, 2026

You are given a string compressed representing a compressed version of a string. The format is a character followed by its frequency. For example, "a3b1a1c2" is a compressed version of the string "aaabacc". We seek a better compression with the following conditions: Each character should appear only once in the compressed version. The characters should be in alphabetical order. Return the better compression of compressed. Note: In the better version of compression, the order of letters may change, which is acceptable.

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn better_compression(compressed: String) -> String {
    let bytes = compressed.as_bytes();
    let mut counts = [0i32; 26];
    let mut i = 0;
    while i < bytes.len() {
      let c = (bytes[i] - b'a') as usize;
      i += 1;
      let mut num = 0;
      while i < bytes.len() && bytes[i].is_ascii_digit() {
        num = num * 10 + (bytes[i] - b'0') as i32;
        i += 1;
      }
      counts[c] += num;
    }
    let mut result = String::new();
    for c in 0..26 {
      if counts[c] > 0 {
        result.push((b'a' + c as u8) as char);
        result.push_str(&counts[c].to_string());
      }
    }
    result
  }
}