Generate tag for video caption

String Simulation

32.3% acceptance

Feb 25, 2026

Generate a hashtag for a video caption. Rules: starts with '#', append words (first letter capitalized, rest lowercase), but first word keeps all lowercase. Remove non-letters. Max 100 chars total. If result is just '#' or longer than 100, return "".

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn generate_tag(caption: String) -> String {
    let mut result = String::from("#");
    let mut first_word = true;
    for word in caption.split_whitespace() {
      // Keep only letters
      let filtered: String = word.chars().filter(|c| c.is_alphabetic()).collect();
      if filtered.is_empty() {
        continue;
      }
      if first_word {
        result.push_str(&filtered.to_lowercase());
        first_word = false;
      } else {
        let mut chars = filtered.chars();
        if let Some(first) = chars.next() {
          result.push(first.to_ascii_uppercase());
          result.push_str(&chars.as_str().to_lowercase());
        }
      }
    }
    if result.len() > 100 {
      result.truncate(100);
    }
    result
  }
}