hsegnitz
diff --git a/‎php/2023/16/01.php
Lines changed: 144 additions & 0 deletions b/‎php/2023/16/01.php
Lines changed: 144 additions & 0 deletions
diff --git a/‎php/2023/16/example.txt
131 Bytes b/‎php/2023/16/example.txt
131 Bytes
diff --git a/‎php/2023/16/input.txt
11.9 KB b/‎php/2023/16/input.txt
11.9 KB
diff --git a/‎php/common/ArrayKeyCache.php
Lines changed: 5 additions & 0 deletions b/‎php/common/ArrayKeyCache.php
Lines changed: 5 additions & 0 deletions
@@ -0,0 +1,144 @@
+<?php
+
+namespace Year2023\Day16;
+
+$start = microtime(true);
+
+#$in = file('example.txt', FILE_IGNORE_NEW_LINES);
+$in = file('input.txt', FILE_IGNORE_NEW_LINES);
+
+$mirrorMap = [];
+foreach ($in as $line) {
+    $mirrorMap[] = str_split($line);
+}
+
+class BeamTracer {
+    private array $seenCoords = [];
+    private array $seenCoordAndDirections = [];
+    public function __construct(private readonly array $mirrorMap)
+    {}
+
+    public function trace(int $x, int $y, string $direction): void
+    {
+        do {
+            $cKey = "$x-$y";
+            $this->seenCoords[$cKey] = true;
+            $cdKey = "$x-$y-$direction";
+            if (isset($this->seenCoordAndDirections[$cdKey])) {
+                return;  // loop detected
+            }
+            $this->seenCoordAndDirections[$cdKey] = true;
+
+            [$x, $y] = $this->walk($x, $y, $direction);
+            if (!isset($this->mirrorMap[$y][$x])) {
+                return;
+            }
+            $tile = $this->mirrorMap[$y][$x];
+            if ($tile === ".") {
+                continue;
+            }
+
+            if ($tile === '/') {
+                $direction = match($direction) {
+                    "R" => 'U',
+                    "L" => 'D',
+                    "U" => 'R',
+                    "D" => 'L',
+                };
+                continue;
+            }
+
+            if ($tile === '\\') {
+                $direction = match($direction) {
+                    "R" => 'D',
+                    "L" => 'U',
+                    "U" => 'L',
+                    "D" => 'R',
+                };
+                continue;
+            }
+
+            if ($tile === '-') {
+                if ($direction === 'D' || $direction === 'U') {
+                    $this->trace($x, $y, 'L');
+                    $this->trace($x, $y, 'R');
+                    return;
+                }
+                continue;
+            }
+
+            if ($tile === '|') {
+                if ($direction === 'L' || $direction === 'R') {
+                    $this->trace($x, $y, 'U');
+                    $this->trace($x, $y, 'D');
+                    return;
+                }
+                continue;
+            }
+
+        } while (isset($this->mirrorMap[$y][$x]));
+    }
+
+
+    private function walk (int $x, int $y, string $direction): array
+    {
+        return match ($direction) {
+            "R" => [$x+1, $y],
+            "L" => [$x-1, $y],
+            "U" => [$x,   $y-1],
+            "D" => [$x,   $y+1],
+        };
+    }
+
+    public function countCoords(): int
+    {
+        return count($this->seenCoords)-1; // the initial tile is out of the map!
+    }
+
+    public function printMap(): void
+    {
+        foreach ($this->mirrorMap as $y => $row) {
+            foreach ($row as $x => $cell) {
+                if (isset($this->seenCoords["$x-$y"])) {
+                    echo "#";
+                } else {
+                    echo ".";
+                }
+            }
+            echo "\n";
+        }
+        echo "\n";
+    }
+}
+
+$tracer = new BeamTracer($mirrorMap);
+$tracer->trace(-1, 0, 'R');
+
+echo "\nPart 1:", $tracer->countCoords(), "\n";
+
+$results = [];
+for ($y = 0, $yMax = count($mirrorMap); $y < $yMax; $y++) {
+    $tracer = new BeamTracer($mirrorMap);
+    $tracer->trace(-1, $y, 'R');
+    $results[] = $tracer->countCoords();
+
+    $tracer = new BeamTracer($mirrorMap);
+    $tracer->trace(count($mirrorMap[$y]), $y, 'L');
+    $results[] = $tracer->countCoords();
+}
+
+for ($x = 0, $xMax = count($mirrorMap[0]); $x < $xMax; $x++) {
+    $tracer = new BeamTracer($mirrorMap);
+    $tracer->trace($x, -1, 'D');
+    $results[] = $tracer->countCoords();
+
+    $tracer = new BeamTracer($mirrorMap);
+    $tracer->trace($x, count($mirrorMap), 'U');
+    $results[] = $tracer->countCoords();
+}
+
+echo "Part2: ", max($results), "\n";
+
+echo microtime(true) - $start;
+echo "\n";
+
@@ -22,4 +22,9 @@ public function retrieve(array $key): mixed
     {
         return $this->cache[$this->makeKey($key)] ?? null;
     }
+
+    public function has(array $key): bool
+    {
+        return isset($this->cache[$this->makeKey($key)]);
+    }
 }
Original file line number	Diff line number	Diff line change
`@@ -22,4 +22,9 @@ public function retrieve(array $key): mixed`
`22`	`22`	`{`
`23`	`23`	`return $this->cache[$this->makeKey($key)] ?? null;`
`24`	`24`	`}`
	`25`	`+`
	`26`	`+ public function has(array $key): bool`
	`27`	`+ {`
	`28`	`+ return isset($this->cache[$this->makeKey($key)]);`
	`29`	`+ }`
`25`	`30`	`}`