Initial data commit

Task/CUSIP/Common-Lisp/cusip.lisp

@@ -0,0 +1,23 @@
+(defun char->value (c)
+  (cond ((digit-char-p c 36))
+        ((char= c #\*) 36)
+        ((char= c #\@) 37)
+        ((char= c #\#) 38)
+        (t (error "Invalid character: ~A" c))))
+
+(defun cusip-p (cusip)
+  (and (= 9 (length cusip))
+       (loop for i from 1 to 8
+             for c across cusip
+             for v = (char->value c)
+             when (evenp i)
+               do (setf v (* 2 v))
+             sum (multiple-value-bind (quot rem) (floor v 10)
+                   (+ quot rem))
+               into sum
+             finally (return (eql (digit-char-p (char cusip 8))
+                                  (mod (- 10 (mod sum 10)) 10))))))
+
+(defun main ()
+  (dolist (cusip '("037833100" "17275R102" "38259P508" "594918104" "68389X106" "68389X105"))
+    (format t "~A: ~A~%" cusip (cusip-p cusip))))