LeetCode--Unique Morse Code Words

题目大意[1]：给定一个字符串列表，每个字符串都由26个小写英文字母组成，每个字串长度都在[1,12]，列表长度不超过100。26个小写字母从a到z分别映射到

[".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."]

求映射之后得到的字符串列表去重后的长度。

for example：给定一个字符串列表，如["gin", "zen", "gig", "msg"]按上述变换成为

"gin" -> "--...-."
"zen" -> "--...-."
"gig" -> "--...--."
"msg" -> "--...--."

去重后为"--...-." and "--...--."，即长度为2。

很简单，直接上代码：

---

class Solution:
    def uniqueMorseRepresentations(self, words):
        """
        :type words: List[str]
        :rtype: int
        """
        dt = {'a':".-","b":"-...","c":"-.-.","d":"-..","e":".","f":"..-.","g":"--.","h":"....","i":"..","j":".---","k":"-.-","l":".-..","m":"--","n":"-.","o":"---","p":".--.","q":"--.-","r":".-.","s":"...","t":"-","u":"..-","v":"...-","w":".--","x":"-..-","y":"-.--","z":"--.."}
        if len(words)>180 or len(words)<=0:
            return 0
        else:
            value = ""
            length =[]
            for i in range(0,len(words)):
                for j in range(0,len(words[i])):
                    v = dt.get(words[i][j])
                    value += v
                length.append(value)
                value = ""
        return len(set(length))
        

然而，发现了一个更pythonic的写法[2]：

def uniqueMorseRepresentations(self, words):
        d = [".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--",
             "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."]
        return len({''.join(d[ord(i) - ord('a')] for i in w) for w in words})

有人会问，ord()是啥，别急，我们瞅瞅看。看python文档里说[3]:

ord(c)

Given a string of length one, return an integer representing the Unicode code point of the character when the argument is a unicode object, or the value of the byte when the argument is an 8-bit string. For example, ord('a') returns the integer 97, ord(u'\u2020') returns 8224. This is the inverse of chr() for 8-bit strings and of unichr() for unicode objects. If a unicode argument is given and Python was built with UCS2 Unicode, then the character’s code point must be in the range [0..65535] inclusive; otherwise the string length is two, and a TypeError will be raised.

翻译成人话就是把字母转化成对应ASCII码。

       

Ref：

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[1] https://leetcode.com/problems/unique-morse-code-words/description/

[2] https://leetcode.com/problems/unique-morse-code-words/discuss/120675/C++JavaPython-Easy-and-Concise-Solution

[3] https://docs.python.org/2/library/functions.html#ord