chore: make language folders snake_case

4 files changed, 267 insertions, 0 deletions

diff --git a/2024/php/day_04/Grid.php b/2024/php/day_04/Grid.php
new file mode 100644
index 0000000..75d531b
--- /dev/null
+++ b/2024/php/day_04/Grid.php
@@ -0,0 +1,69 @@
+<?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/php/day_04/Input.php b/2024/php/day_04/Input.php
new file mode 100644
index 0000000..60a16a0
--- /dev/null
+++ b/2024/php/day_04/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/php/day_04/Position.php b/2024/php/day_04/Position.php
new file mode 100644
index 0000000..0dcf96c
--- /dev/null
+++ b/2024/php/day_04/Position.php
@@ -0,0 +1,79 @@
+<?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/php/day_04/part_01.php b/2024/php/day_04/part_01.php
new file mode 100644
index 0000000..0faa5b0
--- /dev/null
+++ b/2024/php/day_04/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;