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