diff options
Diffstat (limited to '2022')
| -rw-r--r-- | 2022/puzzle-8.lisp | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/2022/puzzle-8.lisp b/2022/puzzle-8.lisp index 426ae13..38c5421 100644 --- a/2022/puzzle-8.lisp +++ b/2022/puzzle-8.lisp @@ -5,3 +5,48 @@ (defparameter trees (mapcar (lambda (line) (mapcar (lambda (char) (parse-integer (string char))) (string-to-clist line))) lines)) +;; Size of a row or column +(defparameter n-trees (length trees)) + +(defun get-column (x) + (loop for row in trees + collect (nth x row))) + +(defun get-row (y) + (nth y trees)) + +(defun get-tree (x y) + (nth x (nth y trees))) + +(defun is-visible? (x y) + (if (or (= x 0) (= x (- n-trees 1)) + (= y 0) (= y (- n-trees 1))) + t + (let* ((tree (get-tree x y)) + (lt-tree? (lambda (a) (< a tree))) + (row (get-row y)) + (row-left (subseq row 0 x)) + (row-right (subseq row (+ x 1))) + (col (get-column x)) + (col-top (subseq col 0 y)) + (col-bottom (subseq col (+ y 1)))) + (or + (all lt-tree? row-left) + (all lt-tree? row-right) + (all lt-tree? col-top) + (all lt-tree? col-bottom))))) + +(defun how-many-visible () + (loop + for x from 0 to (- n-trees 1) + sum + (reduce + #'+ + (loop + for y from 0 to (- n-trees 1) + if (is-visible? x y) + collect 1 + else + collect 0)))) + +(format t "round 1: ~s~%" (how-many-visible)) |