AoC day 5, stupid solution

day5.lisp

(defun read-coords (path)
  (with-open-file (stream path :direction :input :if-does-not-exist :error)
    (let ((res (make-array 0 :adjustable t :fill-pointer 0)))
      (loop :for (x1 y1 _ x2 y2)
              := (uiop:split-string (read-line stream nil nil) :separator ", ")
            :while x1
            :do (vector-push-extend (list (parse-integer x1)
                                          (parse-integer y1)
                                          (parse-integer x2)
                                          (parse-integer y2)) res))
      res)))



(defun max-coord (array)
  (loop :for (x1 y1 x2 y2) :across array
        :maximize (max x1 y1 x2 y2)))


(defun day5.1 (path)
  (let* ((coords (read-coords path))
         (max (max-coord coords))
         (table (make-array (list (+ 1 max) (+ 1 max)) :element-type 'fixnum)))
    (loop :for (x1 y1 x2 y2) :across coords
          :when (= x1 x2)
            :do (loop :for i :from (min y1 y2) :to (max y1 y2)
                      :do (incf (aref table i x1)))
          :when (= y1 y2)
            :do (loop :for i :from (min x1 x2) :to (max x1 x2)
                      :do (incf (aref table y1 i))))
    (loop :for i :from 0 :to max
          :sum (loop :for j :from 0 :to max
                     :count (> (aref table i j) 1)))))


(defun day5.2 (path)
  (let* ((coords (read-coords path))
         (max (max-coord coords))
         (table (make-array (list (+ 1 max) (+ 1 max)) :element-type 'fixnum)))
    (loop :for (x1 y1 x2 y2) :across coords
          :when (= x1 x2)
            :do (loop :for i :from (min y1 y2) :to (max y1 y2)
                      :do (incf (aref table i x1)))
          :when (= y1 y2)
            :do (loop :for i :from (min x1 x2) :to (max x1 x2)
                      :do (incf (aref table y1 i)))
          :when (= (abs (- x1 x2)) (abs (- y1 y2)))
            :do
                (do ((x x1 (if (> x1 x2) (- x 1) (+ x 1)))
                     (y y1 (if (> y1 y2) (- y 1) (+ y 1))))
                    ((= x x2))
                  (incf (aref table y x)))
                (incf (aref table y2 x2)))
    (loop :for i :from 0 :to max
          :sum (loop :for j :from 0 :to max
                     :count (> (aref table i j) 1)))))