LeetCode80|反转字符串中的元音字母

示例 1：

输入："hello"
输出："holle"
示例 2：

输入："leetcode"
输出："leotcede"
 

提示：

元音字母不包含字母 "y" 。

 

 
import java.util.HashSet;
import java.util.stream.Collectors;
import java.util.stream.Stream;

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

    public static String reverseVowels(String s) {
        HashSet<Character> hashSet = new HashSet<>(Stream.of('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U').collect(Collectors.toList()));
        if (s == null || s.length() == 0) {
            return s;
        }
        int i = 0;
        int j = s.length() - 1;
        char[] result = new char[s.length()];
        while (i <= j) {
            char ci = s.charAt(i);
            char cj = s.charAt(j);
            if (!hashSet.contains(ci)) {
                result[i++] = ci;
            } else if (!hashSet.contains(cj)) {
                result[j--] = cj;
            } else {
                result[i++] = cj;
                result[j--] = ci;
            }
        }
        return new String(result);
    }
}