From eaa41f0afb3ff099eb3a04456c9aeff8964748c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment?= <clement@desmidt.fr>
Date: Tue, 15 Dec 2020 10:18:05 +0100
Subject: [PATCH] :construction: Commence le jour 13

---
 day_13/part_1.php | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 day_13/part_1.php

diff --git a/day_13/part_1.php b/day_13/part_1.php
new file mode 100644
index 0000000..40f1d26
--- /dev/null
+++ b/day_13/part_1.php
@@ -0,0 +1,24 @@
+<?php
+
+$input = file_get_contents('input.txt');
+
+[$earliest_timestamp, $buses] = explode("\n", $input);
+
+$earliest_timestamp = (int) $earliest_timestamp;
+
+$buses = array_filter(
+    array_map(static function ($bus) {
+        return $bus === 'x' ? null : (int) $bus;
+    }, explode(',', $buses))
+);
+
+$timestamp = $earliest_timestamp;
+while (true) {
+    foreach ($buses as $bus) {
+        if ($timestamp % $bus === 0) {
+            echo ($timestamp - $earliest_timestamp) * $bus;
+            exit;
+        }
+    }
+    $timestamp++;
+}
\ No newline at end of file