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.

class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        String[] MORSE = new String[]{".-","-...","-.-.","-..",".","..-.","--.",
                         "....","..",".---","-.-",".-..","--","-.",
                         "---",".--.","--.-",".-.","...","-","..-",
                         "...-",".--","-..-","-.--","--.."};

        Set<String> seen = new HashSet();
        for (String word: words) {
            StringBuilder code = new StringBuilder();
            for (char c: word.toCharArray())
                code.append(MORSE[c - 'a']);
            seen.add(code.toString());
        }

        return seen.size();
    }
}