Data commit

Task/Caesar-cipher/Common-Lisp/caesar-cipher-1.lisp

@@ -0,0 +1,19 @@
+(defun encipher-char (ch key)
+  (let* ((c  (char-code  ch)) (la (char-code #\a)) (ua (char-code #\A))
+         (base (cond ((<= la c (char-code #\z)) la)
+                     ((<= ua c (char-code #\Z)) ua)
+                     (nil))))
+    (if base (code-char (+ (mod (+ (- c base) key) 26) base)) ch)))
+
+(defun caesar-cipher (str key)
+  (map 'string #'(lambda (c) (encipher-char c key)) str))
+
+(defun caesar-decipher (str key) (caesar-cipher str (- key)))
+
+(let* ((original-text "The five boxing wizards jump quickly")
+       (key 3)
+       (cipher-text (caesar-cipher original-text key))
+       (recovered-text (caesar-decipher cipher-text key)))
+  (format t " Original: ~a ~%" original-text)
+  (format t "Encrypted: ~a ~%" cipher-text)
+  (format t "Decrypted: ~a ~%" recovered-text))

Task/Caesar-cipher/Common-Lisp/caesar-cipher-2.lisp

@@ -0,0 +1,9 @@
+(defun caesar-encipher (s k)
+  (map 'string #'(lambda (c) (z c k)) s))
+
+(defun caesar-decipher (s k) (caesar-encipher s (- k)))
+
+(defun z (h k &aux (c (char-code  h))
+                   (b (or (when (<= 97 c 122) 97)
+                          (when (<= 65 c 90) 65))))
+  (if b (code-char (+ (mod (+ (- c b) k) 26) b)) h))

Task/Caesar-cipher/Common-Lisp/caesar-cipher-3.lisp

@@ -0,0 +1,9 @@
+(defconstant +a+ "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz")
+
+(defun caesar (txt offset)
+  (map 'string
+    #'(lambda (c)
+        (if (find c +a+)
+          (char +a+ (mod (+ (position c +a+) (* 2 offset)) 52))
+          c))
+    txt))