src/2017/days/day-15.lisp @ a1c5d160d738
Cleanup
author |
Steve Losh <steve@stevelosh.com> |
date |
Fri, 03 Dec 2021 12:43:45 -0500 |
parents |
182bdd87fd9e |
children |
(none) |
(advent:defpackage* :advent/2017/15)
(in-package :advent/2017/15)
(defun-inline gen (previous factor)
(rem (* previous factor) 2147483647))
(defun-inline gen-harder (previous factor divisor)
(iterate
(for x :seed previous :then (gen x factor))
(finding x :such-that (dividesp x divisor))))
(defun-inline matchp (a b)
(= (ldb (byte 16 0) a)
(ldb (byte 16 0) b)))
(define-problem (2017 15) (data read-numbers) (650 336)
(destructuring-bind (a-start b-start) data
(values
(iterate
(repeat 40000000)
(for a :seed a-start :then (gen a 16807))
(for b :seed b-start :then (gen b 48271))
(counting (matchp a b)))
(iterate
(repeat 5000000)
(for a :seed a-start :then (gen-harder a 16807 4))
(for b :seed b-start :then (gen-harder b 48271 8))
(counting (matchp a b))))))