src/2018/days/day-11.lisp @ 9ceb59a426ad
Remove unused macro
author |
Steve Losh <steve@stevelosh.com> |
date |
Sat, 07 Dec 2019 16:58:49 -0500 |
parents |
cd781337a694 |
children |
182bdd87fd9e |
(defpackage :advent/2018/11 #.cl-user::*advent-use*
(:shadow :x :y))
(in-package :advent/2018/11)
(defun cell (x y)
(complex x y))
(defun x (cell)
(realpart cell))
(defun y (cell)
(imagpart cell))
(defun rack-id (cell)
(+ (x cell) 10))
(defun power-level (serial-number cell)
(-<> (rack-id cell)
(* <> (y cell))
(+ <> serial-number)
(* <> (rack-id cell))
(nth-digit 2 <>)
(- <> 5)))
(define-problem (2018 11) (serial-number read) ("245,14" "235,206,13")
(let ((totals (make-array (list 300 300))))
(flet ((gref (x y)
(let ((x (1- x))
(y (1- y)))
(if (array-in-bounds-p totals x y)
(aref totals x y)
0)))
((setf gref) (value x y)
(setf (aref totals (1- x) (1- y)) value)))
(iterate (for-nested ((x :from 300 :downto 1)
(y :from 300 :downto 1)))
(setf (gref x y)
(+ (power-level serial-number (cell x y))
(gref (1+ x) y)
(gref x (1+ y))
(- (gref (1+ x) (1+ y))))))
(labels ((square-power (x y n)
(let ((xn (+ x n))
(yn (+ y n)))
(+ (gref x y)
(- (gref xn y))
(- (gref x yn))
(gref xn yn))))
(largest-square (n)
(iterate
(for-nested ((x :from 1 :to (- 301 n))
(y :from 1 :to (- 301 n))))
(for power = (square-power x y n))
(finding (list x y power) :maximizing power))))
(values (str:join "," (subseq (largest-square 3) 0 2))
(iterate (for n :from 1 :to 300)
(for (x y power) = (largest-square n))
(finding (format nil "~D,~D,~D" x y n)
:maximizing power)))))))