In the Unique Morse Code Words interview question, you are given a mapping of the 26 lowercase English letters to their Morse code representations. Given an array of strings, you must transform each word into its Morse code equivalent by concatenating the Morse codes of its individual letters. Your goal is to return the number of unique Morse code transformations among all the words in the list.
This Unique Morse Code Words coding problem is an introductory-level challenge used by companies like Bloomberg to test basic coding fluency. It evaluates how you handle array indexing (mapping 'a' to index 0, 'b' to 1, etc.) and your ability to use a Set to find unique elements. It’s a straightforward test of "Implementation" skills.
The Array, Hash Table, String interview pattern here is simple transformation and collection. You first store the 26 Morse code strings in an array. For each word in the input, you iterate through its characters, look up their Morse code in the array (using char - 'a' as the index), and append them to a new string. You then add this resulting Morse string to a Hash Set. The count of unique strings in the Set is the final answer.
Given words = ["gin", "zen"]:
--., 'i' -> .., 'n' -> -. => "gin" -> --...-.--.., 'e' -> ., 'n' -> -. => "zen" -> --...-.
Both words produce the same Morse code string. If these were the only words, the answer would be 1 because there is only 1 unique transformation.There are few places to fail here, but common issues include off-by-one errors when mapping characters to the Morse array or forgetting to clear the string builder between words. In some languages, manually concatenating many small strings can be slow, so using a string builder class is a better practice.
For easy-level problems, focus on writing the cleanest, most readable code possible. Use meaningful variable names and ensure you handle the character-to-index conversion correctly. This shows the interviewer that you have strong foundations and attention to detail.