✨ Add day 22 part 1

day_22/part_1.php

@@ -0,0 +1,48 @@
+<?php
+
+$cards = range(0, 10006);
+
+$commands = explode("\n", file_get_contents('input.txt'));
+
+function deal_into_new_stack(array $cards)
+{
+    return array_reverse($cards);
+}
+
+function cut(array $cards, $n_card)
+{
+    $slice = array_splice($cards, 0, $n_card);
+    return array_merge($cards, $slice);
+}
+
+function deal_with_increment(array $cards, $n)
+{
+    $new_cards = [];
+    $deck_length = count($cards);
+    $card_index = 0;
+    $i = 0;
+    while($deck_length !== count($new_cards)) {
+        for (; $i < $deck_length; $i += $n) {
+            $new_cards[$i] = $cards[$card_index];
+            $card_index++;
+        }
+        $i = abs($deck_length - $i);
+    }
+
+    ksort($new_cards);
+    return $new_cards;
+}
+
+foreach ($commands as $command) {
+    if (strpos($command, 'deal with increment') === 0) {
+        $cards = deal_with_increment($cards, (int) substr($command, 20));
+    }
+    if (strpos($command, 'cut') === 0) {
+        $cards = cut($cards, (int) substr($command, 4));
+    }
+    if ('deal into new stack' === $command) {
+        $cards = deal_into_new_stack($cards);
+    }
+}
+
+echo array_search(2019, $cards, true);