L804.java

import java.util.HashSet;
import java.util.Set;

class Solution804 {
    class Solution {
        private final String[] MORSE = new String[]{".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};
        /**
         * 804. Unique Morse Code Words https://leetcode.com/problems/unique-morse-code-words/description/
         *
         * @param words String[]
         *              The list of input words to be transformed to Morse
         * @return The number of unique morse transformations
         * @timeComplexity O(n) where n is the number of chars in all words
         * @spaceComplexity O(n) where n is the number of chars in all unique transformations
         */
        public int uniqueMorseRepresentations(String[] words) {
            Set<String> transformations = new HashSet<>();
            for (String word : words) {
                StringBuffer sb = new StringBuffer();
                for (char c : word.toCharArray()) {
                    sb.append(MORSE[c - 'a']);
                }
                transformations.add(sb.toString());
            }
            return transformations.size();

            // Alternate and slower one liner accepted solution
            // Arrays.asList(words).stream().map(word -> word.chars().mapToObj(c -> MORSE[c - 'a']).collect(Collectors.joining())).collect(Collectors.toSet()).size();*/
        }
    }
}