804_unique_morse_code_words.md

Unique Morse Code Words

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

Solution

class Solution:
    def uniqueMorseRepresentations(self, words: List[str]) -> int:
        codes = set()
        lookup = {
            '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': '--..'
        }

        for word in words:
            wordmorse = ''
            for char in word:
                wordmorse += lookup[char]
            codes.add(wordmorse)
        return len(codes)