804. 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.

class Solution {
public:
    int uniqueMorseRepresentations(vector<string>& words) {
        vector<string> morse = {".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};
        unordered_set<string> us;
        for(auto& w : words) {
            string code = "";
            for(auto& ch : w) {
                code += morse[ch-'a'];
            }
            us.insert(code);
        }
        return us.size();
    }
};