804. Unique Morse Code Words

二刷 08/2022

Version #1 HashSet

Time O(ML) - M is number of words, L is the average length of words

Space O(ML)

Runtime: 2 ms, faster than 99.55% of Java online submissions for Unique Morse Code Words.

Memory Usage: 39.8 MB, less than 99.94% of Java online submissions for Unique Morse Code Words.

class Solution {

    public int uniqueMorseRepresentations(String[] words) {

        String[] map = new String[]{

            ".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."

        };

        Set<String> visited = new HashSet<>();

        for (String word : words) {

            StringBuilder sb = new StringBuilder();

            for (int i = 0; i < word.length(); i++) {

                sb.append(map[word.charAt(i) - 'a']);

            }

            visited.add(sb.toString());

        }

        return visited.size();

    }

}

一刷
90.21 %
class Solution {
    public int uniqueMorseRepresentations(String[] words) {
        if (words == null || words.length == 0) return 0;
        String[] dict = new String[]{".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};
        Set<String> set = new HashSet<>();
        StringBuilder sb = new StringBuilder();
        for (String word : words) {
            for (int i = 0; i < word.length(); i++) {
                sb.append(dict[word.charAt(i) - 'a']);
            }
            set.add(sb.toString());
            sb.setLength(0);
        }
        return set.size();
    }
}