1.10 Reverse Vowels of String

Description

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".

Method

two pointer

Time and Space Complexity

o(n)

Code

public class Solution {

  public String reverseVowels(String s) {
       if (s == null || s.length() <= 1){
           return s;
       }
       char[] strs = s.toCharArray();
       int l = 0;
       int r = s.length() - 1;
       while (l < r){
              while (l < r && !isVowel(strs[l])){
                    l++;
              }
              while (l < r && !isVowel(strs[r])){
                    r--;
              }
              char c = strs[l];
              strs[l] = strs[r];
              strs[r] = c;
              l++;
              r--;
       }
       return new String(strs);
}

private boolean isVowel(char s){
        s = Character.toLowerCase(s);
        if (s == 'a' || s == 'e' || s == 'i' || s == 'o' || s == 'u'){
            return true;
        }
        return false;
}

}