【Leetcode】Reverse Vowels of a String

题目链接：https://leetcode.com/problems/reverse-vowels-of-a-string/

题目：

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".

思路：

easy

算法：

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);     }