struct Solution; impl Solution { pub fn reverse_vowels(s: String) -> String { let (mut i, mut j) = (0, s.len().checked_sub(1).unwrap_or(0)); let mut cs = s.chars().collect::<Vec<char>>(); while i < j { if !Self::is_vowel(cs[i].to_ascii_lowercase()) { i += 1; continue } if !Self::is_vowel(cs[j].to_ascii_lowercase()) { j -= 1; continue } cs.swap(i, j); i += 1; j -= 1; } cs.iter().collect() } fn is_vowel(c: char) -> bool { match c { 'a' | 'e' | 'i' | 'o' | 'u' => true, _ => false } } } fn main() { let s = "hello".to_string(); print!("{}", Solution::reverse_vowels(s)); }