66 lines
1.7 KiB
PHP
66 lines
1.7 KiB
PHP
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<?php
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namespace AdventOfCode21;
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class Day7 extends AbstractCommand
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{
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/**
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* {@inheritdoc}
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*/
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protected static int $day = 7;
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/**
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* {@inheritdoc}
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*/
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protected function part1(array $data): int
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{
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return $this->calculateFuel($data[0], forPart2: false);
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}
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/**
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* {@inheritdoc}
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*/
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protected function part2(array $data): int
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{
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return $this->calculateFuel($data[0], forPart2: true);
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}
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/**
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* @param string $data
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* @param bool $forPart2
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*
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* @return int
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*/
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protected function calculateFuel(string $data, bool $forPart2 = false): int
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{
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$crabs = array_map(static fn (string $crab) => (int) $crab, explode(',', $data));
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/** @psalm-param array{int: int} $fuelPerPosition */
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$fuelPerPosition = [];
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for ($position = min($crabs); $position <= max($crabs); ++$position) {
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foreach ($crabs as $crab) {
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if (!isset($fuelPerPosition[$position])) {
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$fuelPerPosition[$position] = 0;
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}
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$consumption = abs($position - $crab);
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if ($forPart2) {
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$newConsumption = 0;
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// I'm sure there's another way than brute-forcing, but hey, this also works!
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for ($steps = 1; $steps <= $consumption; ++$steps) {
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$newConsumption += $steps;
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}
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$consumption = $newConsumption;
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}
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$fuelPerPosition[$position] += $consumption;
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}
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}
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/** @psalm-suppress ArgumentTypeCoercion */
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return min($fuelPerPosition);
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}
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}
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