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".

 

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import java.util.Arrays;import java.util.HashSet;class Solution {        private final static HashSet
      
        vowels =             new HashSet<>(Arrays.asList('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'));    public String reverseVowels(String s) {        int len = s.length();        int i = 0, j = len - 1;        char[] result = new char[s.length()];        while(i <= j) {            char ci = s.charAt(i);            char cj = s.charAt(j);            if(!vowels.contains(ci)) {                result[i++] = ci;            } else if(!vowels.contains(cj)) {                result[j--] = cj;            } else {                result[i++] = cj;                result[j--] = ci;            }        }        return new String(result); //    }    }
      

 

import java.util.Arrays;import java.util.HashSet;class Solution {    public String reverseVowels(String s) {        if(s == null || s.length() == 0) return s;        int i = 0, j = s.length() - 1;        char[] str = s.toCharArray();        while(i < j) {            if(isVolwe(str[i]) && isVolwe(str[j])) {                char tmp = str[i];                str[i] = str[j];                str[j] = tmp;                i++;                j--;            }            else if(!isVolwe(str[i])) {                i++;            } else {                j--;            }        }        return new String(str);    }    private boolean isVolwe(char ch) {        ch = Character.toLowerCase(ch);        return ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u';     }}