Aufgabe 2 Codewars

README.me

@@ -0,0 +1,3 @@
+Codewars
+Aufgabe 1 Snail: https://www.codewars.com/kata/521c2db8ddc89b9b7a0000c1
+Aufgabe 2 Vigenère Cipher Helper: https://www.codewars.com/kata/52d1bd3694d26f8d6e0000d3

src/codewars/vigenere_cipher_helper.py

@@ -0,0 +1,65 @@
+class VigenereCipher(object):
+    def __init__(self, key, alphabet):
+        self.key = key
+        self.alphabet = alphabet
+
+    def encode(self, text):
+        key = (self.key * ((len(text) // len(self.key)) + 1))[: len(text)]
+
+        result = []
+        idx = 0
+
+        for text_char in text:
+            if text_char not in self.alphabet:
+                result.append(text_char)
+                idx += 1
+            elif (
+                self.alphabet.index(text_char) + self.alphabet.index(key[idx])
+                <= len(self.alphabet) - 1
+            ):
+                result.append(
+                    self.alphabet[
+                        self.alphabet.index(text_char) + self.alphabet.index(key[idx])
+                    ]
+                )
+                idx += 1
+            else:
+                result.append(
+                    self.alphabet[
+                        self.alphabet.index(text_char)
+                        + self.alphabet.index(key[idx])
+                        - len(self.alphabet)
+                    ]
+                )
+                idx += 1
+
+        return "".join(result)
+
+    def decode(self, text):
+        key = (self.key * ((len(text) // len(self.key)) + 1))[: len(text)]
+
+        result = []
+        idx = 0
+
+        for text_char in text:
+            if text_char not in self.alphabet:
+                result.append(text_char)
+                idx += 1
+            elif self.alphabet.index(text_char) - self.alphabet.index(key[idx]) >= 0:
+                result.append(
+                    self.alphabet[
+                        self.alphabet.index(text_char) - self.alphabet.index(key[idx])
+                    ]
+                )
+                idx += 1
+            else:
+                result.append(
+                    self.alphabet[
+                        self.alphabet.index(text_char)
+                        - self.alphabet.index(key[idx])
+                        + len(self.alphabet)
+                    ]
+                )
+                idx += 1
+
+        return "".join(result)