leetcode-74-

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描述

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:

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

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.

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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.

分析

题目的意思是给定一个字符串数组，求可以表示这些字符串的摩斯码有多少（某些单词的摩斯码是一样的），用集合类型可以达到去重的目的。在 Java 中可以使用 HashSet。

解决方案1(Java)

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class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        String[] morseCode = new String[] {".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
        Set<String> result = new HashSet<>();
        for (String word: words) {
            String item = "";
            for(char c: word.toCharArray()) {
                item += morseCode[c-'a'];
            }
            result.add(item);
        }
        return result.size();
    }
}

题目来源