[LeetCode] 804. Unique Morse Code Words

轉自LeetCode

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.

<Solution>

想法如下

• 做 mapping 轉換，然後把答案存到 HashSet，這樣就可以找出不重複的字串了

code 如下

Java

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

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