feat(day 12): implement message decoder supporting forward and backward alphabet shifts

Author: JohnSunny21

FreeCodeCamp/CodingQ/en-de.py

@@ -0,0 +1,77 @@
+"""
+Message Decoder
+Given a secret message string, and an integer representing the number of letters that were used to shift the message to encode it, return the decoded string.
+
+A positive number means the message was shifted forward in the alphabet.
+A negative number means the message was shifted backward in the alphabet.
+Case matters, decoded characters should retain the case of their encoded counterparts.
+Non-alphabetical characters should not get decoded.
+
+=========================================================
+O/P =============>
+
+decode("Xlmw mw e wigvix qiwweki.", 4) should return "This is a secret message."
+decode("Byffi Qilfx!", 20) should return "Hello World!"
+
+"""
+
+def decode_own(message, shift):
+    final = ''
+    if shift < 0:
+        for i in message:
+            if (i != " " and i.isalpha()):
+                code = ord(i) + shift
+                final += chr(code)
+            else:
+                final += i
+    else:
+        for i in message:
+            if (i != " " and i.isalpha()):
+                code = ord(i) - shift
+                final += chr(code)
+            else:
+                final += i
+    
+    return final
+
+
+
+def decode(message, shift):
+    final = ''
+    if shift > 0:
+
+        for i in message:
+            if i.isalpha():
+                base = ord('A') if i.isupper() else ord('a')
+                code = (ord(i) - base - shift) % 26 + base
+                final += chr(code)
+            else:
+                final += i
+    else:
+        for i in message:
+            if i.isalpha():
+                base = ord('A') if i.isupper() else ord('a')
+                code = (ord(i) - base - shift) % 26 + base
+                final += chr(code)
+            else:
+                final += i
+    return final
+
+def decode2(message, shift):
+    final = ''
+    for char in message:
+        if char.isalpha():
+            # Determine ASCII base depending on case
+            base = ord('A') if char.isupper() else ord('a')
+            # Reverse the shift direction for decoding
+            decoded_char = chr((ord(char) - base - shift) % 26 + base)
+            final += decoded_char
+        else:
+            # Keep non-alphabet characters as-is
+            final += char
+    return final
+
+print(decode("Zqd xnt njzx?", -1))
+
+
+# print(decode("Xlmw mw e wigvix qiwweki.", 4))