90 lines
1.9 KiB
PHP
90 lines
1.9 KiB
PHP
<?php
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namespace trizz\AdventOfCode\Y21;
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use JetBrains\PhpStorm\Immutable;
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use trizz\AdventOfCode\Solution;
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final class Day6 extends Solution
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{
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public static null|int|string $part1ExampleResult = 5934;
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public static null|int|string $part1Result = 350917;
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public static null|int|string $part2ExampleResult = 26_984_457_539;
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public static null|int|string $part2Result = 1_592_918_715_629;
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/**
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* @var int[]
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*
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* @psalm-param array{int: int}
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*/
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#[Immutable] private array $startState = [
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8 => 0,
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7 => 0,
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6 => 0,
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5 => 0,
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4 => 0,
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3 => 0,
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2 => 0,
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1 => 0,
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0 => 0,
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];
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#[\Override]
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public function part1(array $data): int
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{
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return $this->processPuzzle(80, $data[0]);
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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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return $this->processPuzzle(256, $data[0]);
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}
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/**
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* @param int[] $state
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*
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* @psalm-param array{int: int} $state
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*/
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private function processDay(array $state): array
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{
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$newState = $state;
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/**
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* @var int $key
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* @var int $stateValue
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*/
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foreach ($state as $key => $stateValue) {
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$newKey = $key - 1;
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if ($newKey < 0) {
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$newState[8] = $stateValue;
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$newKey = 6;
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}
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$newState[$key] -= $stateValue;
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$newState[$newKey] += $stateValue;
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}
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return $newState;
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}
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private function processPuzzle(int $numberOfDays, string $data): int
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{
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$state = $this->startState;
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array_map(static function (string $stateValue) use (&$state): void {
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++$state[(int) $stateValue];
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}, explode(',', $data));
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for ($day = 0; $day < $numberOfDays; ++$day) {
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$state = $this->processDay($state);
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}
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return (int) array_sum($state);
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}
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}
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