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

// Example 1:

// Given s = "hello", return "holle".

// Example 2:

// Given s = "leetcode", return "leotcede".

// Note:

// The vowels does not include the letter "y".

public class Solution {

public String reverseVowels(String s) {

if(s == null || s.length() == 0) return s;

String vowels = "aeiouAEIOU";

char[] chars = s.toCharArray();

int start = 0;

int end = s.length() - 1;

while(start < end) {

while(start < end && !vowels.contains(chars[start] + "")) {

start++;

}

while(start < end && !vowels.contains(chars[end] + "")) {

end--;

}

char temp = chars[start];

chars[start] = chars[end];

chars[end] = temp;

start++;

end--;

}

return new String(chars);

}

}