#![allow(dead_code)]

// double pointers
pub fn reverse_vowels(s: String) -> String {
    if s.len() < 1 {
        return s;
    }
    let mut i = 0;
    let mut j = s.len() - 1;
    let mut res = s.chars().collect::<Vec<char>>();
    while i < j {
        while i < s.len() && !is_vowel(res[i]) {
            i += 1;
        }
        while j > 0 && !is_vowel(res[j]) {
            j -= 1;
        }
        if i < j {
            res.swap(i, j);
            i += 1;
            j -= 1;
        }
    }
    res.iter().collect::<String>()
}

// other express method for double pointers
pub fn reverse_vowels2(s: String) -> String {
    if s.len() < 1 {
        return s;
    }
    let mut i = 0;
    let mut j = s.len() - 1;
    let mut res = s.chars().collect::<Vec<char>>();
    while i < j {
        if !is_vowel(res[i]) {
            i += 1;
            continue;
        }
        if !is_vowel(res[j]) {
            j -= 1;
            continue;
        }
        if i < j {
            res.swap(i, j);
        }
        i += 1;
        j -= 1;
    }
    res.iter().collect::<String>()
}

fn is_vowel(c: char) -> bool {
    match c {
        'a' | 'A' | 'e' | 'E' | 'i' | 'I' | 'o' | 'O' | 'u' | 'U' => true,
        _ => false,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test1() {
        assert_eq!(
            reverse_vowels(String::from("leetcode")),
            String::from("leotcede")
        );

        assert_eq!(reverse_vowels(String::from(".")), String::from("."));
    }

    #[test]
    fn test2() {
        assert_eq!(
            reverse_vowels2(String::from("leetcode")),
            String::from("leotcede")
        );

        assert_eq!(reverse_vowels2(String::from(".")), String::from("."));
    }
}