leetcode reversevowelsofastring

import java.util.HashMap;
import java.util.HashSet;

public class  {
  
   * Write a function that takes a string as input and reverse only the vowels of a string.
   * <p>
   * Example 1:
   * <p>
   * Input: "hello"
   * Output: "holle"
   * Example 2:
   * <p>
   * Input: "leetcode"
   * Output: "leotcede"
   */
  public String reverseVowels(String s) {
    HashSet<Character> vowels = new HashSet<>();
    char[] sc = s.toCharArray();
    vowels.add('a');
    vowels.add('e');
    vowels.add('i');
    vowels.add('o');
    vowels.add('u');
    int left = 0;
    int right = s.length() - 1;
    while (left < right) {
      if (vowels.contains(sc[left]) && vowels.contains(sc[right])) {
        char t = sc[left];
        sc[left] = sc[right];
        sc[right] = t;
      }
      if (!vowels.contains(sc[left])) left++;
      if (!vowels.contains(sc[right])) right--;
    }
    StringBuilder sb = new StringBuilder();
    for (char c: sc){
      sb.append(c);
    }
    return sb.toString();
  }
}