From 9b0f2cfdb58a9633a0da2427270fbffd768a90df Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Tue, 19 Dec 2017 10:19:37 +0100
Subject: [PATCH] Even simpler bounds check.

---
 2017/day-19/solution.php | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/2017/day-19/solution.php b/2017/day-19/solution.php
index 4207e56..969d5f4 100755
--- a/2017/day-19/solution.php
+++ b/2017/day-19/solution.php
@@ -11,16 +11,16 @@ $dir = [0, 1];
 $path = '';
 $steps = 0;
 
-while ($maze[$y][$x] != ' ') {
+while (($maze[$y][$x] ?? ' ') != ' ') {
     if (ctype_alpha($maze[$y][$x])) {
         $path .= $maze[$y][$x];
     } elseif ($maze[$y][$x] == '+') {
         if ($dir[0] == 0) {
-            $dir[0] = ($x == 0 || $maze[$y][$x - 1] == ' ') ? 1 : -1;
+            $dir[0] = ($maze[$y][$x + 1] ?? ' ') == ' ' ? -1 : 1;
             $dir[1] = 0;
         } else {
             $dir[0] = 0;
-            $dir[1] = ($y == 0 || $maze[$y - 1][$x] == ' ') ? 1 : -1;
+            $dir[1] = ($maze[$y + 1][$x] ?? ' ') == ' ' ? -1 : 1;
         }
     }