345. Reverse Vowels of a String

Write a function that takes a string as input and reverse only the vowels of a string.

Example 1:

```Input: "hello"
Output: "holle"
```

Example 2:

```Input: "leetcode"
Output: "leotcede"```

Note:
The vowels does not include the letter "y".

345. Reverse Vowels of a String
``````struct Solution;

impl Solution {
fn is_vowel(c: char) -> bool {
matches!(c, 'a' | 'e' | 'i' | 'o' | 'u' | 'A' | 'E' | 'I' | 'O' | 'U')
}

fn reverse_vowels(s: String) -> String {
let mut a: Vec<char> = s.chars().collect();
let n = a.len();
if n == 0 {
return "".to_string();
}
let mut l = 0;
let mut r = n - 1;
while l < r {
if Self::is_vowel(a[l]) && Self::is_vowel(a[r]) {
a.swap(l, r);
l += 1;
r -= 1;
} else {
if !Self::is_vowel(a[l]) {
l += 1;
}
if !Self::is_vowel(a[r]) {
r -= 1;
}
}
}
a.iter().collect()
}
}

#[test]
fn test() {
let s = "hello".to_string();
let t = "holle".to_string();
assert_eq!(Solution::reverse_vowels(s), t);
let s = "leetcode".to_string();
let t = "leotcede".to_string();
assert_eq!(Solution::reverse_vowels(s), t);
let s = "a.".to_string();
let t = "a.".to_string();
assert_eq!(Solution::reverse_vowels(s), t);
}
``````