4 files changed, 263 insertions, 0 deletions
diff --git a/2024/OCaml/lib/day_04/php/Grid.php b/2024/OCaml/lib/day_04/php/Grid.php
new file mode 100644
index 0000000..c0382df
--- /dev/null
+++ b/2024/OCaml/lib/day_04/php/Grid.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+class Grid implements Stringable
+{
+	/**
+	 * @param string[][] $data
+	 */
+	public function __construct(public array $data) {}
+
+	public function __toString(): string
+	{
+		$rowToLine = fn(array $row): string => array_reduce(
+			array: $row,
+			callback: fn(string $acc, string $character): string => $acc . $character,
+			initial: "",
+		);
+
+		return array_reduce(
+			array: $this->data,
+			callback: fn(string $acc, array $row): string => $acc . $rowToLine($row) . PHP_EOL,
+			initial: "",
+		);
+	}
+
+	public function getCharacterAtPosition(Position $position): string
+	{
+		if ($this->isInBounds($position)) {
+			return $this->data[$position->y][$position->x];
+		}
+
+		return ".";
+	}
+
+	/**
+	 * @param Position[] $positions
+	 */
+	public function getStringFromPositions(array $positions): string
+	{
+		$characters = array_map(
+			callback: fn(Position $position): string => $this->getCharacterAtPosition($position),
+			array: $positions,
+		);
+
+		$string = array_reduce(
+			array: $characters,
+			callback: fn(string $acc, string $character): string => $acc . $character,
+			initial: "",
+		);
+
+		return $string;
+	}
+
+	public function isInBounds(Position $position): bool
+	{
+		if (!array_key_exists($position->y, $this->data)) {
+			return false;
+		}
+
+		if (!array_key_exists($position->x, $this->data[$position->y])) {
+			return false;
+		}
+
+		return true;
+	}
+}
diff --git a/2024/OCaml/lib/day_04/php/Input.php b/2024/OCaml/lib/day_04/php/Input.php
new file mode 100644
index 0000000..f7e03c1
--- /dev/null
+++ b/2024/OCaml/lib/day_04/php/Input.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+class Input
+{
+	public string $contents;
+
+	public function __construct(private string $fileName)
+	{
+		$contents = file_get_contents($this->fileName, use_include_path: true);
+		$this->contents = $contents === false ? "" : $contents;
+	}
+
+	public function toGrid(): Grid
+	{
+		$lines = explode("\n", $this->contents);
+		$gridArray = array_map(
+			callback: fn(string $line): array => str_split(trim($line)),
+			array: $lines
+		);
+
+		return new Grid($gridArray);
+	}
+}
diff --git a/2024/OCaml/lib/day_04/php/Position.php b/2024/OCaml/lib/day_04/php/Position.php
new file mode 100644
index 0000000..182da7e
--- /dev/null
+++ b/2024/OCaml/lib/day_04/php/Position.php
@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+class Position implements Stringable
+{
+	public function __construct(public $x, public $y) {}
+
+	public function __toString(): string
+	{
+		return "({$this->x}, {$this->y})";
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getNorth(): self
+	{
+		return new self($this->x, $this->y - 1);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getNorthEast(): self
+	{
+		return new self($this->x + 1, $this->y - 1);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getEast(): self
+	{
+		return new self($this->x + 1, $this->y);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getSouthEast(): self
+	{
+		return new self($this->x + 1, $this->y + 1);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getSouth(): self
+	{
+		return new self($this->x, $this->y + 1);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getSouthWest(): self
+	{
+		return new self($this->x - 1, $this->y + 1);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getWest(): self
+	{
+		return new self($this->x - 1, $this->y);
+	}
+
+	/**
+	 * Not validated
+	 */
+	public function getNorthWest(): self
+	{
+		return new self($this->x - 1, $this->y - 1);
+	}
+}
diff --git a/2024/OCaml/lib/day_04/php/part_01.php b/2024/OCaml/lib/day_04/php/part_01.php
new file mode 100644
index 0000000..250da0c
--- /dev/null
+++ b/2024/OCaml/lib/day_04/php/part_01.php
@@ -0,0 +1,94 @@
+<?php
+
+declare(strict_types=1);
+
+spl_autoload_register(fn(string $className) => require "{$className}.php");
+
+// Assumes executed from workspace root
+$input = new Input('input/day_04.txt');
+if ($input->contents === "") {
+    throw new RuntimeException("File not found");
+}
+
+$grid = $input->toGrid();
+
+$matchCount = 0;
+foreach ($grid->data as $y => $row) {
+    foreach ($row as $x => $char) {
+        if ($char !== 'X') {
+            continue;
+        }
+
+        $start = new Position($x, $y);
+
+        $possibleMatches = [];
+
+        $possibleMatches["north"] = $grid->getStringFromPositions([
+            $start,
+            $start->getNorth(),
+            $start->getNorth()->getNorth(),
+            $start->getNorth()->getNorth()->getNorth(),
+        ]);
+
+        $possibleMatches["east"] = $grid->getStringFromPositions([
+            $start,
+            $start->getEast(),
+            $start->getEast()->getEast(),
+            $start->getEast()->getEast()->getEast(),
+        ]);
+
+        $possibleMatches["south"] = $grid->getStringFromPositions([
+            $start,
+            $start->getSouth(),
+            $start->getSouth()->getSouth(),
+            $start->getSouth()->getSouth()->getSouth(),
+        ]);
+
+        $possibleMatches["west"] = $grid->getStringFromPositions([
+            $start,
+            $start->getWest(),
+            $start->getWest()->getWest(),
+            $start->getWest()->getWest()->getWest(),
+        ]);
+
+        $possibleMatches["north-east"] = $grid->getStringFromPositions([
+            $start,
+            $start->getNorthEast(),
+            $start->getNorthEast()->getNorthEast(),
+            $start->getNorthEast()->getNorthEast()->getNorthEast(),
+        ]);
+
+        $possibleMatches["north-west"] = $grid->getStringFromPositions([
+            $start,
+            $start->getNorthWest(),
+            $start->getNorthWest()->getNorthWest(),
+            $start->getNorthWest()->getNorthWest()->getNorthWest(),
+        ]);
+
+        $possibleMatches["south-east"] = $grid->getStringFromPositions([
+            $start,
+            $start->getSouthEast(),
+            $start->getSouthEast()->getSouthEast(),
+            $start->getSouthEast()->getSouthEast()->getSouthEast(),
+        ]);
+
+        $possibleMatches["south-west"] = $grid->getStringFromPositions([
+            $start,
+            $start->getSouthWest(),
+            $start->getSouthWest()->getSouthWest(),
+            $start->getSouthWest()->getSouthWest()->getSouthWest(),
+        ]);
+
+        $matchCount += array_reduce(
+            array: $possibleMatches,
+            callback: fn(int $acc, string $possibleMatch): int => match ($possibleMatch) {
+                "XMAS" => $acc + 1,
+                default => $acc,
+            },
+            initial: 0,
+        );
+    }
+}
+
+// ANSWER: 2517
+echo $matchCount;