2.leetcode唯一的摩斯密码

发布时间:2019-10-12 20:08:40编辑:auto阅读(1810)

    1.题目
    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, "cba" 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 "--...--.".
    1. 自己的解决方法
    class Solution:
        def uniqueMorseRepresentations(self, words: List[str]) -> int:
            final_set = set()
            mosLIst = [".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."]
            for word in words:
                temp = ''
                for i in word:
                    temp += mosLIst[ord(i)-97]
                final_set.add(temp)
            return len(final_set)
    Runtime: 36 ms, faster than 97.45% of Python3 online submissions for Unique Morse Code Words.
    Memory Usage: 12.9 MB, less than 5.36% of Python3 online submissions for Unique Morse Code Words.

    3.其他解决方法

    const codes = [".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."]
    
    const getIdx = char => char.charCodeAt(0) - 'a'.charCodeAt(0)
    
    var uniqueMorseRepresentations = function(words) {
        return words.map( word => word.split('')
                                     .map( char => codes[getIdx(char)])
                                     .join(''))
                    .reduce((set, cur) => set.add(cur), new Set())
                    .size
    };

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