LeetCode No.345 Reverse Vowels of a String

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".

Note:

The vowels does not include the letter "y".

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

题目大意：颠倒字符串中的元音。

思路：记录元音下标，交换前后下标字符。

参考代码：

class Solution {public:    string reverseVowels(string s) {        vector <int> index ;        int n = s.size() ;        for ( int i = 0 ; i < n ; i ++ )            if ( isVowel ( s[i] ) )                index.push_back ( i ) ;        int m = index.size() ;        for ( int i = 0 ; i < m / 2 ; i ++ )        {            char ch = s[index[i]] ;            s[index[i]] = s[index[m-i-1]] ;             s[index[m-i-1]] = ch ;        }        return s ;    }private :    bool isVowel ( char ch )     {          return ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' || ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U';      }  };