824. Goat Latin - Detailed Explanation

Problem Statement

You are given a sentence containing words separated by spaces. Your task is to convert the sentence to "Goat Latin" using the following rules:

1. If a word begins with a vowel (a, e, i, o, u, in either uppercase or lowercase), append "ma" to the end of the word.

2. If a word begins with a consonant, remove the first letter, append it to the end of the word, and then add "ma".

3. After applying the above rule to each word, append one letter 'a' to the end of each word per its word index in the sentence, starting with 1. For the first word, add "a"; for the second word, add "aa"; for the third word, add "aaa"; and so on.

Example 1

• Input: "I speak Goat Latin"
• Output: "Imaa peaksmaaa oatGmaaaa atinLmaaaaa"
• Explanation:
  • Word 1: "I" → Vowel, so becomes "I" + "ma" + "a" = "Imaa"
  • Word 2: "speak" → Consonant, so becomes "peak" + "s" + "ma" + "aa" = "peaksmaaa"
  • Word 3: "Goat" → Consonant, so becomes "oat" + "G" + "ma" + "aaa" = "oatGmaaaa"
  • Word 4: "Latin" → Consonant, so becomes "atin" + "L" + "ma" + "aaaa" = "atinLmaaaaa"

Example 2

• Input: "The quick brown fox jumped over the lazy dog"
• Output:
  • Transformation is done word by word using the same rules.
  • For example, "The" becomes "heTmaa" (since 'T' is a consonant) and so on for each word.

Example 3

• Input: "apple"
• Output: "applemaa"
• Explanation:
  • Since "apple" starts with a vowel, simply append "ma" and then add one "a" for the first word.

Constraints:

• The input sentence is a non-empty string.
• The sentence contains words separated by single spaces.
• Each word consists only of uppercase and lowercase letters.

Hints

1. Hint 1:
   Start by splitting the sentence into individual words. Process each word one by one and keep track of the word index to append the correct number of "a"s at the end.

2. Hint 2:
   Use a set or string containing vowels (both uppercase and lowercase) to easily check if a word starts with a vowel. For each word, based on whether the first character is a vowel or consonant, perform the required transformation.

Approach 1: Brute Force / Straightforward String Manipulation

Explanation

• Step 1: Split the input sentence into words using the space as a delimiter.
• Step 2: Iterate over each word while keeping track of its index (starting from 1).
• Step 3: For each word:
  • Check if the first letter is a vowel.
    • If yes, append "ma" directly to the word.
    • If no, remove the first character, append it to the end of the word, then append "ma".
• Step 4: Append additional "a"s equal to the current word index.
• Step 5: Combine all the transformed words back into a single string with spaces.

Visual Example (Using "I speak Goat Latin")

1. Split:
   ["I", "speak", "Goat", "Latin"]

2. Processing:

   • Word 1 ("I"):
     • Starts with vowel → "I" + "ma" = "Ima"
     • Append one "a": "Imaa"
   • Word 2 ("speak"):
     • Starts with consonant → Remove "s", then "peak" + "s" = "peaks"
     • Append "ma": "peaksma"
     • Append two "a"s: "peaksmaaa"
   • Word 3 ("Goat"):
     • Starts with consonant → Remove "G", then "oat" + "G" = "oatG"
     • Append "ma": "oatGma"
     • Append three "a"s: "oatGmaaaa"
   • Word 4 ("Latin"):
     • Starts with consonant → Remove "L", then "atin" + "L" = "atinL"
     • Append "ma": "atinLma"
     • Append four "a"s: "atinLmaaaaa"

3. Join:
   Combine the processed words with a space:
   "Imaa peaksmaaa oatGmaaaa atinLmaaaaa"

Approach 2: Optimal/Concise Approach

Explanation

The brute force approach described is already optimal for this problem since the overall work is proportional to the number of characters in the sentence. An alternative concise solution might leverage Python’s list comprehension or Java’s StringBuilder in a more compact format. However, the fundamental steps remain the same:

• Split the sentence.
• Process each word using the vowel/consonant rules.
• Append the "ma" and extra "a"s.
• Join the words back into a sentence.

This approach runs in linear time with respect to the total number of characters in the sentence.

Complexity Analysis

• Time Complexity: O(n) where n is the total number of characters in the input sentence. Each character is processed a constant number of times.

• Space Complexity: O(n) for storing the list of words and the final result.

Code in Python