3rd and 2nd day

02/part1.php

@@ -0,0 +1,15 @@
+<?php
+
+$increased   = 0;
+$inputStream = fopen('input', 'r');
+$horizontal  = $depth = 0;
+
+while (($line = fgets($inputStream)) !== false) {
+    [$instruction, $value] = explode(' ', trim($line));
+    match ($instruction) {
+        'down' => $depth += (int)$value,
+        'up' => $depth -= (int)$value,
+        'forward' => $horizontal += (int)$value,
+    };
+}
+echo $depth * $horizontal; // 1635930