824. Goat Latin

Problem

You are given a string sentence that consist of words separated by spaces. Each word consists of lowercase and uppercase letters only.

We would like to convert the sentence to "Goat Latin" (a made-up language similar to Pig Latin.) The rules of Goat Latin are as follows:

If a word begins with a vowel ('a', 'e', 'i', 'o', or 'u'), append "ma" to the end of the word.

• For example, the word "apple" becomes "applema".

  If a word begins with a consonant (i.e., not a vowel), remove the first letter and append it to the end, then add "ma".

• For example, the word "goat" becomes "oatgma".

  Add one letter 'a' to the end of each word per its word index in the sentence, starting with 1.

• For example, the first word gets "a" added to the end, the second word gets "aa" added to the end, and so on.

Return** the final sentence representing the conversion from sentence to Goat Latin**.

  Example 1:

Input: sentence = "I speak Goat Latin"
Output: "Imaa peaksmaaa oatGmaaaa atinLmaaaaa"

Example 2:

Input: sentence = "The quick brown fox jumped over the lazy dog"
Output: "heTmaa uickqmaaa rownbmaaaa oxfmaaaaa umpedjmaaaaaa overmaaaaaaa hetmaaaaaaaa azylmaaaaaaaaa ogdmaaaaaaaaaa"

  Constraints:

• 1 <= sentence.length <= 150

• sentence consists of English letters and spaces.

• sentence has no leading or trailing spaces.

• All the words in sentence are separated by a single space.

Solution (Java)

class Solution {
    public String toGoatLatin(String sentence) {
        String[] splits = sentence.split(" ");
        StringBuilder sb = new StringBuilder();
        StringBuilder a = new StringBuilder();
        for (String word : splits) {
            if (isVowel(word.charAt(0))) {
                sb.append(word).append("ma");
            } else {
                char firstChar = word.charAt(0);
                sb.append(word.substring(1)).append(firstChar).append("ma");
            }
            a.append("a");
            sb.append(a);
            sb.append(" ");
        }
        return sb.toString().trim();
    }

    private boolean isVowel(char c) {
        return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u' || c == 'A' || c == 'E'
                || c == 'I' || c == 'O' || c == 'U';
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).