Leetcode 804 - Unique Morse Code Words

Note:

  • Know how to efficently use split with map.

Question:

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:

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

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:

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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 "--...--.".

Code:

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/**
* @param {string[]} words
* @return {number}
*/
var uniqueMorseRepresentations = function(words) {
let morses = [".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."];
return new Set(words.map(e => e.split('').map(ch => morses[ch.charCodeAt(0) - 'a'.charCodeAt(0)]).join(''))).size;
};