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:

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

Now, given a list of words, 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 "-.-." + "-..." + ".-"). We'll call such a concatenation, the transformation of a word.

Return the number of different transformations among all words we have.

Example:

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 "--...--.".

Note:

• The length of words will be at most 100.
• Each words[i] will have length in range [1, 12].
• words[i] will only consist of lowercase letters.

Analyze

The input is a vector<string> words. There are some words. We need to convert those words to MorseRepresentations. And some works may get the same Mores Code. We need output how many different Mores code can get from these words. As a result, I choose std::unordered_set<std::string> to save these Morse Code. And return its size.

Solution

class Solution {
public:
    int uniqueMorseRepresentations(vector<string>& words) {
      std::string name[26]={".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
      std::unordered_set<std::string> myset;

      for (vector<string>::iterator it = words.begin(); it != words.end(); ++it) {
        std::string tmp = "";
        for (char c : *it ) {
          tmp += name[ c- 'a'];
        }
        myset.insert (tmp);
      }
      return myset.size();
    }
};