345. Reverse Vowels of a String【easy】

345. Reverse Vowels of a String【easy】

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".

解法一：

 class Solution {
 public:
     bool isVowels(char x)
     {
         if (x >= 'A' && x <= 'Z') {
             x += ;
         }
         return (x == 'a' || x == 'e' || x == 'i' || x == 'o' || x == 'u');
     }

     void reverseChar(string &s, int start, int end)
     {
         char temp = s[start];
         s[start] = s[end];
         s[end] = temp;
     }

     string reverseVowels(string s) {
         int start = ;
         int end = s.length() - ;

         while (start < end) {
             while (start < end && !isVowels(s[start])) {
                 ++start;
             }

             while (start < end && !isVowels(s[end])) {
                 --end;
             }

             reverseChar(s, start, end);
             ++start;
             --end;
         }

         return s;
     }
 };

注意循环的条件

 

解法二：

 class Solution {
 public:
     string reverseVowels(string s) {
         int i = , j = s.size() - ;
         while (i < j) {
             i = s.find_first_of("aeiouAEIOU", i);
             j = s.find_last_of("aeiouAEIOU", j);
             if (i < j) {
                 swap(s[i++], s[j--]);
             }
         }
         return s;
     }
 };

参考@tedbear 的代码。