Unique Morse Code Words

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:

[".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."]

Given an array of strings words where each word can be written as a concatenation of the Morse code of each letter.

• For example, "cab" can be written as "-.-..--...", which is the concatenation of "-.-.", ".-", and "-...". We will call such a concatenation the transformation of a word.

Return the number of different transformations among all words we have

LeetCode Problem - 804

class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        // Initialize a map to store the Morse code representation for each letter
        Map<Character, String> mp = new HashMap<>();

        // Array of Morse code representations corresponding to each letter from 'a' to 'z'
        String[] morseCodes = {".-","-...","-.-.","-..",".","..-.","--.","....","..",".---",
                               "-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-",
                               "..-","...-",".--","-..-","-.--","--.."};

        // Populate the map with letters 'a' to 'z' and their corresponding Morse code representations
        char charValue = 'a';
        for(String morseCode : morseCodes) {
            mp.put(charValue, morseCode);
            charValue++;
        }

        // List to store unique Morse code transformations
        List<String> al = new ArrayList<>();

        // Loop through each word in the input array
        for(String word : words) {
            StringBuilder sb = new StringBuilder(); // StringBuilder to construct the Morse code representation of the word

            // Loop through each character in the word
            for(int i = 0; i < word.length(); i++) {
                // Get the Morse code for the current character and append it to the StringBuilder
                String currentMorseCodeValue = mp.get(word.charAt(i));
                sb.append(currentMorseCodeValue);
            }

            // If the Morse code representation is not already in the list, add it to the list
            if(!al.contains(sb.toString())) {
                al.add(sb.toString());
            }
        }

        // Return the number of unique Morse code transformations
        return al.size();
    }
}