Longest word in dictionary through deleting

Array Two Pointers String Sorting

52.5% acceptance

Feb 19, 2026

1863

365

Given a string s and a string array dictionary, return the longest string in the dictionary that can be formed by deleting some of the given string characters. If there is more than one possible result, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.

Solution

Rust

Time O(2^n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn find_longest_word(s: String, dictionary: Vec<String>) -> String {
    fn is_subseq(word: &[u8], s: &[u8]) -> bool {
      let mut j = 0;
      for &c in s {
        if j < word.len() && word[j] == c { j += 1; }
      }
      j == word.len()
    }
    let sb = s.as_bytes();
    let mut result = String::new();
    for word in &dictionary {
      if is_subseq(word.as_bytes(), sb) {
        if word.len() > result.len() || (word.len() == result.len() && word < &result) {
          result = word.clone();
        }
      }
    }
    result
  }
}