better solution of Encode And Decode Tinyurl

Author: P-ppc

algorithms/EncodeAndDecodeTinyurl/README.md

@@ -1,2 +1,45 @@
 # Encode And Decode Tinyurl
-We can solve this problem by hashmap
+We can solve this problem by hashmap, the better solution is like below:
+```python
+class Codec:
+    def __init__(self):
+        self.encode_url_map = {}
+        self.url_encode_map = {}
+        self.base_url = 'http://tinyurl.com/'
+        self.encode_table = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
+    
+    def encode(self, longUrl):
+        """Encodes a URL to a shortened URL.
+        
+        :type longUrl: str
+        :rtype: str
+        """
+        if self.url_encode_map.get(longUrl):
+            return self.base_url + self.url_encode_map.get(longUrl)
+        
+        # i <= pow(62, 6) - 1
+        i = len(self.encode_url_map)
+        
+        encode = ''
+        while i > 0:
+            encode += self.encode_table[i % 62]
+            i /= 62
+        encode = encode.zfill(6)
+        self.url_encode_map[longUrl] = encode
+        self.encode_url_map[encode] = longUrl
+        return self.base_url + encode
+        
+
+    def decode(self, shortUrl):
+        """Decodes a shortened URL to its original URL.
+        
+        :type shortUrl: str
+        :rtype: str
+        """
+        encode = shortUrl.replace(self.base_url, '')
+        return self.encode_url_map.get(encode)
+
+# Your Codec object will be instantiated and called as such:
+# codec = Codec()
+# codec.decode(codec.encode(url))
+```