src/2020/days/day-14.lisp @ 59d313b4c898
Commit some 2023 days
author |
Steve Losh <steve@stevelosh.com> |
date |
Wed, 06 Dec 2023 08:17:12 -0500 |
parents |
68bbcb0ce4f7 |
children |
(none) |
(advent:defpackage* :advent/2020/14)
(in-package :advent/2020/14)
(defun parse (stream)
(iterate
(for line :in-stream stream :using #'read-line)
(collect (or (ppcre:register-groups-bind ((#'parse-integer addr val))
("mem\\[(\\d+)\\] = (\\d+)" line)
(list :set addr val))
(ppcre:register-groups-bind (mask)
("mask = ([X01]+)" line)
(list :mask mask))))))
(defun op (inst) (first inst))
(defun mask (inst) (second inst))
(defun addr (inst) (second inst))
(defun value (inst) (third inst))
(defun-inline char->bit (char)
(ecase char (#\0 0) (#\1 1)))
(defun-inline dpbit (bit pos value)
(dpb bit (byte 1 pos) value))
(defun mask-value (mask value)
(iterate (for char :in-string mask :downto 0)
(for pos :from 0)
(unless (eql #\X char)
(setf value (dpbit (char->bit char) pos value))))
value)
(defun mask-address (mask addr)
(iterate (with-result addrs = (list addr))
(for pos :from 0)
(for char :in-string mask :downto 0)
(ecase char
(#\X (setf addrs (append (mapcar (curry #'dpbit 0 pos) addrs)
(mapcar (curry #'dpbit 1 pos) addrs))))
(#\0 (progn))
(#\1 (map-into addrs (curry #'dpbit 1 pos) addrs)))))
(defun run-program (program &key part)
(iterate (with memory = (make-hash-table))
(with mask = nil)
(for inst :in program)
(ecase (op inst)
(:mask (setf mask (mask inst)))
(:set (ecase part
(1 (setf (gethash (addr inst) memory 0)
(mask-value mask (value inst))))
(2 (dolist (addr (mask-address mask (addr inst)))
(setf (gethash addr memory 0)
(value inst)))))))
(finally (return (reduce #'+ (alexandria:hash-table-values memory))))))
(define-problem (2020 14) (data parse) (9967721333886 4355897790573)
(values
(run-program data :part 1)
(run-program data :part 2)))
#; Scratch --------------------------------------------------------------------