[2018-12-02] Add second challange sample and solution

day2/main.php

@@ -25,6 +25,27 @@ function puzzle1(array $boxIds) : int
     return $counters[2] * $counters[3];
 }
 
+function puzzle2(array $boxIds) : string
+{
+    foreach ($boxIds as $boxId) {
+        foreach ($boxIds as $boxId2) {
+            if ($boxId === $boxId2) {
+                continue;
+            }
+
+            if (levenshtein($boxId, $boxId2) === 1) {
+                for ($i = 0; $i < strlen($boxId); $i++) {
+                    if ($boxId[$i] !== $boxId2[$i]) {
+                        return substr_replace($boxId, '', $i, 1);
+                    }
+                }
+
+                break 2;
+            }
+        }
+    }
+}
+
 echo 'First challange sample:'.PHP_EOL;
 echo puzzle1([
     'abcdef',
@@ -38,3 +59,18 @@ echo puzzle1([
 
 echo 'First challange solution:'.PHP_EOL;
 echo puzzle1(explode(PHP_EOL, trim(file_get_contents(dirname(__FILE__).'/input.txt')))).PHP_EOL.PHP_EOL;
+
+
+echo 'Second challange sample:'.PHP_EOL;
+echo puzzle2([
+    'abcde',
+    'fghij',
+    'klmno',
+    'pqrst',
+    'fguij',
+    'axcye',
+    'wvxyz',
+]).PHP_EOL; // fgij
+
+echo 'Second challange solution:'.PHP_EOL;
+echo puzzle2(explode(PHP_EOL, trim(file_get_contents(dirname(__FILE__).'/input.txt')))).PHP_EOL.PHP_EOL;