LeetCode-in-Java

804. Unique Morse Code Words

Easy

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

import java.util.HashSet;
import java.util.Set;

public class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        String[] morse = {
            ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..",
            "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-",
            "-.--", "--.."
        };
        Set<String> set = new HashSet<>();
        for (String word : words) {
            StringBuilder temp = new StringBuilder();
            for (char c : word.toCharArray()) {
                temp.append(morse[c - 'a']);
            }
            set.add(temp.toString());
        }
        return set.size();
    }
}

This site is open source. Improve this page.