"Leetcode" Reverse vowels of a String

Title Link: https://leetcode.com/problems/reverse-vowels-of-a-string/

Topic:

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".

Ideas:

Easy

Algorithm:

Public String Reversevowels (string s) {char c[] = S.tochararray ();         set<string> vowels = new hashset<string> ();         Vowels.add ("a");         Vowels.add ("E");         Vowels.add ("I");         Vowels.add ("O");         Vowels.add ("U");         Vowels.add ("A");         Vowels.add ("E");         Vowels.add ("I");         Vowels.add ("O");         Vowels.add ("U");         int v1=-1,v2=-1;                  for (int start=0,end=c.length-1;start<end;) {if (v1==-1) {if (Vowels.contains (c[start]+ ""))              V1 = start;          else start++;              } if (V2==-1) {if (Vowels.contains (c[end]+ ")) v2 = end;          else end--;              } if (v1!=-1&&v2!=-1) {char tmp = C[V1];              C[V1] = C[v2];              C[V2] = tmp;              V1 =-1;              v2 =-1;              start++;          end--;      }                 } return new String (c);   }

"Leetcode" Reverse vowels of a String