Leetcode 804. 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:

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

Now, given a list of words, 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 "-.-." + "-..." + ".-"). We'll call such a concatenation, the transformation of a word.

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

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

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

Note:

• 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.

Code (Java):

class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        if (words == null || words.length == 0) {
            return 0;
        }
        
        Set<String> morseCodeSet = new HashSet<>();
        
        int ans = 0;
        
        for (String word : words) {
            String morseCode = GetMorseCode(word);
            
            if (!morseCodeSet.contains(morseCode)) {
                morseCodeSet.add(morseCode);
            }
        }
        
        return morseCodeSet.size();
    }
    
    private String GetMorseCode(String word) {
        String[] morseCodeDict = {".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
        
        String morseCode = "";
        
        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);
            morseCode += morseCodeDict[c - 'a'];
        }
        
        return morseCode;
    }
}