第18位身份证号生成算法

gistfile1.txt

(require 'cl-lib)

(defun personal-identity-last-bit (n)
  ;; 1. S = sum(item(i) * weight(i))
  ;; 2. Y = mod(S, 11)
  ;; 3. M = map(Y, r)
  (let ((bits (mapcar 'string-to-number
                      (mapcar 'char-to-string n)))
        (weights '(7 9 10 5 8 4 2 1 6 3 7 9 10 5 8 4 2))
        (map-result '(1 0 "X" 9 8 7 6 5 4 3 2)))
    (nth (% (apply '+ (cl-mapcar #'* bits weights )) 11) map-result)))