804. Unique Morse Code Words

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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: 2Explanation: The transformation of each word is:"gin" -> "--...-.""zen" -> "--...-.""gig" -> "--...--.""msg" -> "--...--."There are 2 different transformations, "--...-." and "--...--.".

 1 //Time O(n), Space O(n) HashSet 用來去除重複 2  3     public int uniqueMorseRepresentations(String[] words) { 4         String[] map = new String[]{".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."}; 5  6         if (words == null || words.length == 0) { 7             return 0; 8         } 9         10         HashSet<String> result = new HashSet<String>();11         12         for (String word : words) {13             StringBuilder sb = new StringBuilder();14             15             for (int i = 0; i < word.length(); i++) {16                 int loc = word.charAt(i) - ‘a‘;17                 sb.append(map[loc]);18             }19             20             result.add(sb.toString());21         }22         23         return result.size();24     }

 

804. Unique Morse Code Words