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".

Solution:

有点像快排。

public class Solution 
{
    public String reverseVowels(String s) 
    {
        if(s == null || s.length() == 0)
            return "";
        
        char[] chars = s.toCharArray();
        String vowels = "AEIOUaeiou";
        
        int i = 0, j = s.length() - 1;
        while(i < j)
        {
            while(!vowels.contains(chars[i] + ""))
            {
                if(i == s.length() - 1) break;
                i ++;
            }
            while(!vowels.contains(chars[j] + ""))
            {
                if(j == 0)  break;
                j --;
            }
            
            if(i >= j)
                break;
            
            char temp = chars[i];
            chars[i] = chars[j];
            chars[j] = temp;
            
            i++;
            j--;
        }
        
        return new String(chars);
    }
}