Development (#16)

* caesar cipher

* binary to decimal

Author: realDuYuanChao

ciphers/caesar.py

@@ -0,0 +1,41 @@
+"""
+https://en.wikipedia.org/wiki/Caesar_cipher
+"""
+
+
+def encrypt(original: str, steps: int = 3) -> str:
+    """
+    >>> encrypt("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+    'DEFGHIJKLMNOPQRSTUVWXYZABC'
+    >>> encrypt("abcdefghijklmnopqrstuvwxyz")
+    'defghijklmnopqrstuvwxyzabc'
+    """
+    original = list(original)
+    for i in range(0, len(original)):
+        if original[i].isupper():
+            original[i] = chr(65 + (ord(original[i]) - 65 + steps) % 26)
+        elif original[i].islower():
+            original[i] = chr(97 + (ord(original[i]) - 97 + steps) % 26)
+    return "".join(original)
+
+
+def decrypt(password: str, steps: int = 3) -> str:
+    """
+    >>> decrypt("DEFGHIJKLMNOPQRSTUVWXYZABC")
+    'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+    >>> decrypt(("defghijklmnopqrstuvwxyzabc"))
+    'abcdefghijklmnopqrstuvwxyz'
+    """
+    password = list(password)
+    for i in range(0, len(password)):
+        if password[i].isupper():
+            password[i] = chr(65 + (ord(password[i]) - 65 - steps + 26) % 26)
+        elif password[i].islower():
+            password[i] = chr(97 + (ord(password[i]) - 97 - steps + 26) % 26)
+    return "".join(password)
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()

conversions/binary_to_decimal.py

@@ -0,0 +1,29 @@
+"""
+https://en.wikipedia.org/wiki/Binary_number
+https://en.wikipedia.org/wiki/Decimal
+"""
+
+
+def binary_to_decimal(binary: str) -> int:
+    """
+    >>> binary_to_decimal("0")
+    0
+    >>> binary_to_decimal("1")
+    1
+    >>> binary_to_decimal("1010")
+    10
+    >>> binary_to_decimal("-11101")
+    -29
+    """
+    is_negative = binary[0] == "-"
+    binary = binary[1:] if is_negative else binary
+    decimal = 0
+    for i in range(0, len(binary)):
+        decimal += int(binary[i]) * (2 ** (len(binary) - i - 1))
+    return -decimal if is_negative else decimal
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()