Unique Morse Code Words - LeetCode solutions

Problem

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**.

Example 1:

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 "--...--.".

Example 2:

Input: words = ["a"]
Output: 1

Constraints:

1 <= words.length <= 100
1 <= words[i].length <= 12
words[i] consists of lowercase English letters.

Solution

/**
 * @param {string[]} words
 * @return {number}
 */
var uniqueMorseRepresentations = function(words) {
  return new Set(words.map(word => word.split('').map(letter => alphabet[letter]).join(''))).size
};

const alphabet = {
  a: '.-', b: '-...',   c: '-.-.', d: '-..', e: '.', f: '..-.', g: '--.', h: '....', i: '..',  j: '.---',  k: '-.-',  l: '.-..', m: '--',
  n: '-.',  o: '---', p: '.--.',  q: '--.-',  r: '.-.', s: '...', t: '-', u: '..-', v: '...-', w: '.--', x: '-..-',  y: '-.--', z: '--..' 
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).