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：

 1 class Solution {
 
 2 public:
 3     bool isVowels(char x) 
 4     {
 5         if (x >= ‘A‘ && x <= ‘Z‘) {
 6             x += 32;
 7         }
 8         return (x == ‘a‘ || x == ‘e‘ || x == ‘i‘ || x == ‘o‘ || x == ‘u‘); 
 9     }
10     
11     void reverseChar(string &s, int start, int end)
 
12     {
13         char temp = s[start];
14         s[start] = s[end];
15         s[end] = temp;
16     }
17     
18     string reverseVowels(string s) {
19         int start = 0;
20         int end = s.length() - 1;
21         
22         while (start < end) {
23             while (start < end && !isVowels(s[start])) {
 
24                 ++start;
25             }
26             
27             while (start < end && !isVowels(s[end])) {
28                 --end;
29             }
30             
31             reverseChar(s, start, end);
32             ++start;
33             --end;
34         }
35         
36         return s;
37     }
38 };

註意循環的條件

 1 class Solution {
 2 public:
 3     string reverseVowels(string s) {
 4         int i = 0, j = s.size() - 1;
 5         while (i < j) {
 6             i = s.find_first_of("aeiouAEIOU", i);
 7             j = s.find_last_of("aeiouAEIOU", j);
 8             if (i < j) {
 9                 swap(s[i++], s[j--]);
10             }
11         }
12         return s;
13     }
14 };

參考@tedbear 的代碼。

345. Reverse Vowels of a String【easy】