UniqueMorseCodeWords804.java

/**
 * 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.
 */

public class UniqueMorseCodeWords804 {
    private String[] MOSRE_TABLE = new String[]{".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
    public int uniqueMorseRepresentations(String[] words) {
        Set<String> set = new HashSet<>();
        for (String word: words) {
            set.add(getMorseCode(word));
        }
        return set.size();
    }

    private String getMorseCode(String word) {
        StringBuilder sb = new StringBuilder();
        for (char ch: word.toCharArray()) {
            sb.append(MOSRE_TABLE[ch-'a']);
        }
        return sb.toString();
    }

}