(in-package #:adventofcode2020)

;;; Utility functions

(defun list-from (str)
  (split "\\n" str))

(defun int-list-from (str)
  (mapcar #'parse-integer (list-from str)))

(defun list-list-from (str)
  (split-sequence "" (list-from str) :test #'string=))

(defun cartesian-product (A B &rest C)
  (let ((helper (lambda (X Y)
                  (if Y (loop for x in X
                              nconc (loop for y in Y
                                          collecting (append x (list y))))
                      X)))
        (wrap-A (mapcar #'list A)))
    (reduce helper C :initial-value (funcall helper wrap-A B))))

(defun manhattan-distance (a b)
  (destructuring-bind ((ax ay) (bx by)) (list a b)
    (+ (abs (- ax bx))
       (abs (- ay by)))))

(def-suite util)
(in-suite util)

(test cart-prod-2
  (is (equal
        '((a a) (a b) (b a) (b b))
        (cartesian-product '(a b) '(a b)))))

(test cart-prod-3
  (is (equal
        '((a a a) (a a b) (a b a) (a b b) 
                  (b a a) (b a b) (b b a) (b b b))
        (cartesian-product '(a b) '(a b) '(a b)))))

(test cart-prod-4
  (is (equal
        '((a a a a) (a a a b) (a a b a) (a a b b) (a b a a) (a b a b) (a b b a) (a b b b)
                    (b a a a) (b a a b) (b a b a) (b a b b) (b b a a) (b b a b) (b b b a) (b b b b))
        (cartesian-product '(a b) '(a b) '(a b) '(a b)))))