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Title:Unique Morse Code Words 804
Difficulty:Easy
原题leetcode地址: https://leetcode.com/problems/unique-morse-code-words/
1. Set集合的唯一性
时间复杂度:O(n^2),嵌套for循环。
空间复杂度:O(n),申请了Set,最长是字符串数组的长度。
/**
* Set集合的唯一性
* @param words
* @return
*/
public static int uniqueMorseRepresentations(String[] words) {
String sm[] = {".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
Set<String> set = new HashSet<>();
for (String word : words) {
StringBuilder sb = new StringBuilder();
for (char c : word.toCharArray()) {
sb.append(sm[c - 'a']);
}
set.add(sb.toString());
}
return set.size();
}