(defpackage #:rucksacks
  (:use :cl))
(in-package #:rucksacks)
(defvar *rucksacks* ())
(defun chars (s) (loop for c across s collect c))
(with-open-file (s "./list.txt")
  (setf *rucksacks*
	(loop for line = (read-line s nil)
	while line collect
	(let ((half (floor (length line) 2)))
	  (let ((s1 (subseq line 0 half)) (s2 (subseq line half)))
	    (list (chars s1) (chars s2)))))))
(defun items-in-both (x y) 
  (loop for e in x
	when (member e y) collect e))
(defun char-to-priority (c)
  (let ((x (char-code c)))
    (cond ((and (>= x (char-code #\a)) (<= x (char-code #\z))) (+ 1 (- x (char-code #\a))))
	  ((and (>= x (char-code #\A)) (<= x (char-code #\Z))) (+ 27 (- x (char-code #\A))))
	  (t 0))))
(let ((duplicates (mapcar #'(lambda (x) (items-in-both (car x) (car (cdr x)))) *rucksacks*)))
  (let ((tmp (loop for e in duplicates collect (mapcar #'char-to-priority e))))
    (print (reduce #'+ (loop for e in tmp collect (reduce #'+ (remove-duplicates e)))))))