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 "--...--.". ~~~ ~~~ var morse = [".-","-...","-.-.","-..",".","..-.","--.","....", "..",".---","-.-",".-..","--","-.","---", ".--.","--.-",".-.","...","-","..-","...-", ".--","-..-","-.--","--.."]; function to_morse(word){ var ret = []; for(i in word){ var c = word[i].charCodeAt() - 'a'.charCodeAt(); s = morse[c]; ret.push(s); } return ret.join(''); } var uniqueMorseRepresentations = function(words){ d = {}; var num =0; for(j in words){ var s = to_morse(words[j]); if(!(s in d)){ num++; } d[s] = 1; } return num; } ~~~ > 思路：將將每個word轉換成morse碼，轉換方法是先計算出每個word中的每個字母與字母a的距離，然后就可以從數組 alphabet中取到每個字母的morse碼，然后將一個word中的每一個Morse碼拼接起來；在遍歷所有的words時候，將每個word對應的morse碼定義為某個對象的屬性，循環一次就判斷一下該屬性是否在這個對象中，不在的話，num++； 注意，不要忘記給對象的屬性賦值，否則會出錯