From 55902dc9b6263e46abbf7e78c10a27958f3a5f06 Mon Sep 17 00:00:00 2001
From: Matthew Gretton-Dann <matt@gretton-dann.org.uk>
Date: Sat, 16 Dec 2023 09:57:44 +0000
Subject: [PATCH] 2023 Day 16 Part 2 code tidy

We can simplify (but obfuscate) some of the beam direction calculations.
---
 2023/puzzle-16-02.cc | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/2023/puzzle-16-02.cc b/2023/puzzle-16-02.cc
index 545cf44..c0156db 100644
--- a/2023/puzzle-16-02.cc
+++ b/2023/puzzle-16-02.cc
@@ -131,21 +131,15 @@ private:
         case '.':
           break;
         case '\\':
-          if (beam.dir_ == north) { beam.dir_ = west; }
-          else if (beam.dir_ == east) { beam.dir_ = south; }
-          else if (beam.dir_ == south) { beam.dir_ = east; }
-          else if (beam.dir_ == west) { beam.dir_ = north; }
-          else { std::abort(); }
+          std::swap(beam.dir_.first, beam.dir_.second);
           break;
         case '/':
-          if (beam.dir_ == north) { beam.dir_ = east; }
-          else if (beam.dir_ == east) { beam.dir_ = north; }
-          else if (beam.dir_ == south) { beam.dir_ = west; }
-          else if (beam.dir_ == west) { beam.dir_ = south; }
-          else { std::abort(); }
+          std::swap(beam.dir_.first, beam.dir_.second);
+          beam.dir_.first = -beam.dir_.first;
+          beam.dir_.second = -beam.dir_.second;
           break;
         case '|':
-          if (beam.dir_ == east || beam.dir_ == west) {
+          if (beam.dir_.second == 0) {
             Beam beam2{beam};
             beam2.dir_ = north;
             beam2.loc_ = beam2.loc_ + beam2.dir_;
@@ -154,7 +148,7 @@ private:
           }
           break;
         case '-':
-          if (beam.dir_ == north || beam.dir_ == south) {
+          if (beam.dir_.first == 0) {
             Beam beam2{beam};
             beam2.dir_ = east;
             beam2.loc_ = beam2.loc_ + beam2.dir_;