90 lines
2.5 KiB
PHP
90 lines
2.5 KiB
PHP
<?php
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namespace trizz\AdventOfCode\Y23;
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final class Day4 extends \trizz\AdventOfCode\Solution
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{
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public static null|int|string $part1ExampleResult = 13;
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public static null|int|string $part1Result = 24733;
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public static null|int|string $part2ExampleResult = 30;
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public static null|int|string $part2Result = 5_422_730;
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private mixed $scoringNumbersPerCard;
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private int $totalCards;
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private mixed $numberOfCards;
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#[\Override]
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public function part1(array $data): int
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{
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$score = 0;
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foreach ($data as $line) {
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[$winningNumbers, $cardNumbers] = $this->parseInput($line);
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$scoringNumbers = array_intersect($winningNumbers, $cardNumbers);
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if ($scoringNumbers === []) {
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continue;
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}
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$cardScore = 1;
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for ($i = 0; $i < count($scoringNumbers) - 1; ++$i) {
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$cardScore *= 2;
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}
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$score += $cardScore;
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}
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return $score;
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}
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#[\Override]
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public function part2(array $data): int
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{
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$this->totalCards = count($data);
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foreach ($data as $card => $line) {
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[$winningNumbers, $cardNumbers] = $this->parseInput($line);
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$scoringNumbers = array_intersect($winningNumbers, $cardNumbers);
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$this->scoringNumbersPerCard[$card] = count($scoringNumbers);
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$this->numberOfCards[$card] = 1;
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}
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// Start the recursive loop with the first card.
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$this->updateCount(0);
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return array_sum($this->numberOfCards);
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}
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public function updateCount(int $card): void
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{
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$cardCount = $this->numberOfCards[$card] ?? 0;
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for ($i = 0; $i < $cardCount; ++$i) {
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$winningNumbers = $this->scoringNumbersPerCard[$card] ?? 0;
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for ($number = 1; $number <= $winningNumbers; ++$number) {
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++$this->numberOfCards[$card + $number];
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}
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}
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if ($card <= $this->totalCards) {
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$this->updateCount($card + 1);
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}
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}
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/**
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* @return array<int, array<int>>
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*/
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public function parseInput(string $input): array
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{
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$numbers = explode(':', $input)[1];
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[$winningNumbers, $cardNumbers] = explode('|', $numbers, 2);
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$winningNumbers = array_map('intval', array_filter(explode(' ', $winningNumbers)));
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$cardNumbers = array_map('intval', array_filter(explode(' ', $cardNumbers)));
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return [$winningNumbers, $cardNumbers];
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}
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}
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