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".
Solution：前后two pointers, 交换vowels
Time Complexity: O(N) Space Complexity: O(N)
Solution Code：
class Solution {
public String reverseVowels(String s) {
if(s == null || s.length()==0) return s;
String vowels = "aeiouAEIOU";
char[] chars = s.toCharArray();
int i = 0, j = s.length() - 1;
while(i < j){
// skip non-vowels
while(i < j && !vowels.contains(chars[i] + "")) i++;
while(i < j && !vowels.contains(chars[j] + "")) j--;
// change vowels
char tmp = chars[i];
chars[i] = chars[j];
chars[j] = tmp;
i++;
j--;
}
return new String(chars);
}
}
