Leetcode Easy


International Morse Code defines a standard encoding where each letter is mapped to a series of dots and dashes, as follows: "a" maps to ".-", "b" maps to "-...", "c" maps to "-.-.", and so on.

For convenience, the full table for the 26 letters of the English alphabet is given below:


Now, given a list of words, each word can be written as a concatenation of the Morse code of each letter. For example, “cba” can be written as “-.-..–…”, (which is the concatenation “-.-.” + “-…” + “.-“). We’ll call such a concatenation, the transformation of a word.

Return the number of different transformations among all words we have.

Input: words = ["gin", "zen", "gig", "msg"]
Output: 2
The transformation of each word is:
"gin" -> "--...-."
"zen" -> "--...-."
"gig" -> "--...--."
"msg" -> "--...--."

There are 2 different transformations, "--...-." and "--...--.".


  • The length of words will be at most 100.
  • Each words[i] will have length in range [1, 12].
  • words[i] will only consist of lowercase letters.


class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        String[] morse = new String[]{".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
        HashSet<String> uniqueWords = new HashSet<>();

        for (String word : words) {
            StringBuilder translation = new StringBuilder();
            for (int i = 0; i < word.length(); i++) {
                // Append the morse representation of the current letter
                translation.append(morse[word.charAt(i) - 'a']);


        return uniqueWords.size();

Why this works

Because a hashSet does not store duplicates, we can add every translation to the hashSet and simply return the size, as it will be the size of the words array minus the number of duplicates.