【Leetcode】804. Unique Morse Code Words

Unique Morse Code Words

Description

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.

Discuss

把字母对应的字符串存起来，一次遍历每一个单词，然后去重就可以了。

Code

class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        List<String> list = Arrays.asList(".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..",
                "--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--..");
        Map<Integer, String> map = new HashMap<>();
        int ans = 0;
        for (int i = 97; i <= 122; i++) {
            map.put(i, list.get(ans++));
        }
        Set<String> set = new HashSet<>();
        for (int i = 0; i < words.length; i++) {
            StringBuilder sb = new StringBuilder();
            for (int j = 0; j < words[i].length(); j++) {
                sb.append(map.get(Integer.valueOf(words[i].charAt(j))));
            }
            set.add(sb.toString());
        }
        return set.size();
    }
}