src/2017/days/day-14.lisp @ 03d0cc3a648f
2019/14
author |
Steve Losh <steve@stevelosh.com> |
date |
Sat, 14 Dec 2019 12:47:15 -0500 |
parents |
cd781337a694 |
children |
182bdd87fd9e |
(defpackage :advent/2017/14 #.cl-user::*advent-use*)
(in-package :advent/2017/14)
(defun print-grid (grid)
(dotimes (row 128)
(dotimes (col 128)
(princ (if (aref grid row col) #\# #\.)))
(terpri)))
(defun gref (grid point)
(let-complex ((row col point))
(when (and (in-range-p 0 row 128)
(in-range-p 0 col 128))
(aref grid row col))))
(defun (setf gref) (new-value grid point)
(setf (aref grid (realpart point) (imagpart point)) new-value))
(defun flood-region (grid row col)
(iterate
(with seen = (make-hash-set))
(with frontier = (make-hash-set :initial-contents (list (complex row col))))
(until (hset-empty-p frontier))
(for next = (hset-pop! frontier))
(when (not (hset-contains-p seen next))
(hset-insert! seen next)
(when (gref grid next)
(counting t)
(setf (gref grid next) nil)
(apply #'hset-insert! frontier (manhattan-neighbors next))))))
(define-problem (2017 14) (data read-line) (8226 1128)
(multiple-value-bind (grid total)
(iterate
(with grid = (make-array '(128 128)))
(for row :from 0 :to 127)
(for hash = (advent/knot-hash:full-knot-hash
(format nil "~A-~D" data row)
:result-type 'integer))
(summing (logcount hash) :into total)
(dotimes (col 128)
(setf (aref grid row col)
(logbitp (- 127 col) hash)))
(returning grid total))
(values total
(iterate
(for-nested ((row :from 0 :to 127)
(col :from 0 :to 127)))
(counting (plusp (flood-region grid row col)))))))