LeetCode345 Reverse Vowels of a String

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博客给出一道LeetCode题目，要求编写函数反转字符串中的元音字母，给出示例及注意事项，元音不包含字母 'y'，并指出使用对撞指针解决该问题。

题目：

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".

本题使用对撞指针解决问题

public class ReverseVowels {
    public static String reverseVowels(String s) {
        if (null == s || "".equals(s))
            return s;
        int l = 0;
        int r = s.length() - 1;
        char[] charArray = s.toCharArray();
        while (l <= r){
            if (!isVowel(charArray[l])){
                l++;
                continue;
            }
            if (!isVowel(charArray[r])){
                r--;
                continue;
            }
            swap(charArray, l++, r--);
        }
        return String.valueOf(charArray);
    }

    public static boolean isVowel(char c){
        char lowerCh = Character.toLowerCase(c);
        if (lowerCh == 'a' || lowerCh == 'e' || lowerCh == 'i' || lowerCh == 'o' || lowerCh == 'u')
            return true;
        return false;
    }

    public static void swap(char[] charArray, int i, int j){
        char temp = charArray[i];
        charArray[i] = charArray[j];
        charArray[j] = temp;
    }

    public static void main(String[] args) {
        String s = "leetcode";
        System.out.println(reverseVowels(s));
    }
}