804. Unique Morse Code Words

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.

Rust Solution

struct Solution;

use std::collections::HashSet;

impl Solution {
    fn unique_morse_representations(words: Vec<String>) -> i32 {
        let map = [
            ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..",
            "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-",
            "-.--", "--..",
        ];
        let mut morse: HashSet<String> = HashSet::new();
        for w in words {
            let mut s: String = "".to_string();
            for c in w.chars() {
                let m = map[(c as u8 - b'a') as usize];
                s += m;
            }
            morse.insert(s);
        }
        morse.len() as i32
    }
}

#[test]
fn test() {
    let words: Vec<String> = vec_string!["gin", "zen", "gig", "msg"];
    assert_eq!(Solution::unique_morse_representations(words), 2);
}

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