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;;; solver.el --- Day 10 -*- lexical-binding: t; -*-
;;
;; Copyright (C) 2022 Óscar Nájera
;;
;; Author: Óscar Nájera <hi@oscarnajera.com>
;; Maintainer: Óscar Nájera <hi@oscarnajera.com>
;; Created: December 10, 2022
;; Modified: December 10, 2022
;;
;; This file is not part of GNU Emacs.
;;
;;; Commentary:
;;
;; Day 10
;;
;;; Code:
(require 'f)
(require 'subr-x)
(require 'cl-lib)
(require 'ert)
(defsubst solver-probe (cycle register)
(when (memq cycle '(20 60 100 140 180 220))
(* cycle register)))
(let ((register 1)
(cycle 1)
measures)
(dolist (instruction (split-string (f-read "input") "\n"))
(cl-incf cycle)
(let ((step1 (solver-probe cycle register)) ;; the noop default
(step2 ;; addx takes 2 cycles
(when (string-prefix-p "addx" instruction)
(cl-incf cycle)
(cl-incf register (string-to-number (cadr (split-string instruction))))
(solver-probe cycle register))))
(when-let ((probe (or step1 step2)))
(push probe measures))))
(list (reverse measures)
(apply #'+ measures)
cycle))
(provide 'solver)
;;; solver.el ends here
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