✨ Finit le 1er jour

day_1/part_1.php

@@ -0,0 +1,11 @@
+<?php
+
+$numbers = array_map('intval', explode("\n", file_get_contents('input.txt')));
+
+foreach ($numbers as $number) {
+    $number_to_2020 = 2020 - $number;
+    if (in_array($number_to_2020, $numbers, true)) {
+        echo $number_to_2020 * $number;
+        exit;
+    }
+}

day_1/part_2.php

@@ -0,0 +1,22 @@
+<?php
+
+$numbers = array_map('intval', explode("\n", file_get_contents('input.txt')));
+
+foreach ($numbers as $i => $number_1) {
+    foreach ($numbers as $j => $number_2) {
+        if ($j <= $i) {
+            continue;
+        }
+
+        if ($number_1 + $number_2 >= 2020) {
+            continue;
+        }
+
+        $number_to_2020 = 2020 - $number_1 - $number_2;
+
+        if (in_array($number_to_2020, $numbers, true)) {
+            echo $number_to_2020 * $number_1 * $number_2;
+            exit;
+        }
+    }
+}