✨ Finit le jour 1

day_1/part_1.php

@@ -0,0 +1,20 @@
+<?php
+
+$list_1 = [];
+$list_2 = [];
+
+$lines = array_filter(explode("\n", file_get_contents(__DIR__.'/input.txt')), static fn($line) =>!empty($line));
+
+foreach ($lines as $line) {
+    [$a, $b] = explode("   ", $line);
+    $list_1[] = $a;
+    $list_2[] = $b;
+}
+
+sort($list_1); sort($list_2);
+$total = 0;
+for ($i=0, $l=count($list_1); $i < $l; $i++) {
+    $total += abs($list_1[$i] - $list_2[$i]);
+}
+
+echo $total;

day_1/part_2.php

@@ -0,0 +1,21 @@
+<?php
+
+$list_1 = [];
+$list_2 = [];
+
+$lines = array_filter(explode("\n", file_get_contents(__DIR__.'/input.txt')), static fn($line) =>!empty($line));
+
+foreach ($lines as $line) {
+    [$a, $b] = explode("   ", $line);
+    $list_1[] = $a;
+    $list_2[] = $b;
+}
+
+$similarity_score = 0;
+
+$count_list_2 = array_count_values($list_2);
+foreach ($list_1 as $item) {
+    $similarity_score += array_key_exists($item, $count_list_2) ? $count_list_2[$item] * $item : 0;
+}
+
+echo $similarity_score;