Goat Latin

Goat Latin

What is this problem about?

The Goat Latin interview question is a string manipulation task. You are given a sentence consisting of words separated by spaces. You need to convert the sentence to "Goat Latin" following three specific rules:

1. If a word begins with a vowel ('a', 'e', 'i', 'o', or 'u'), 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, and then add "ma".
3. Add one letter 'a' to the end of each word based on its word index in the sentence, starting with 1 (e.g., the first word gets "a", the second gets "aa", etc.).

Why is this asked in interviews?

Companies like Apple and Meta use this String interview pattern as a warm-up or screening question. It tests a candidate's ability to follow a precise set of instructions and handle basic string operations (splitting, character checking, and concatenation). It evaluates if you can write clean, bug-free code for a problem with multiple edge cases (like uppercase vs. lowercase vowels).

Algorithmic pattern used

This problem uses a String Splitting and Simulation pattern.

1. Split: Split the input sentence by spaces into an array of words.
2. Iterate: Loop through the words while keeping track of the current index (1-based).
3. Conditionals: For each word, check the first character (converted to lowercase for easy comparison).
4. Transform: Apply the vowel or consonant rule.
5. Append: Append the appropriate number of 'a's using the index.
6. Join: Reconstruct the sentence by joining the transformed words with spaces.

Example explanation

Sentence: "I speak Goat Latin"

1. Word 1 ("I"): Starts with vowel. Add "ma" -> "Ima". Add 1 'a' -> "Imaa".
2. Word 2 ("speak"): Starts with consonant 's'. Move 's' to end -> "peaks". Add "ma" -> "peaksma". Add 2 'a's -> "peaksmaaa".
3. Word 3 ("Goat"): Consonant 'G'. Move 'G' -> "oatG". Add "ma" -> "oatGma". Add 3 'a's -> "oatGmaaaa".
4. Word 4 ("Latin"): Consonant 'L'. Move 'L' -> "atinL". Add "ma" -> "atinLma". Add 4 'a's -> "atinLmaaaaa". Result: "Imaa peaksmaaa oatGmaaaa atinLmaaaaa".

Common mistakes candidates make

• Case Sensitivity: Forgetting that vowels can be uppercase ('A', 'E', 'I', 'O', 'U').
• String Concatenation Overhead: Using += in a loop in languages where strings are immutable (like Java), leading to $O(N^2)$ memory usage. Using a StringBuilder or list join is better.
• Off-by-One: Starting the 'a' count at 0 instead of 1.

Interview preparation tip

Whenever you need to check if a character belongs to a specific set (like vowels), creating a predefined Set<Character> or a helper function isVowel(char) makes the code much cleaner and less error-prone than a long if statement.