63 lines
1.3 KiB
PHP
63 lines
1.3 KiB
PHP
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<?php
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namespace AdventOfCode21;
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class Day1 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 = 1;
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/**
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* {@inheritdoc}
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*/
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protected function part1(array $data): int
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{
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$previous = null;
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$increases = 0;
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/** @var int $current */
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foreach ($data as $current) {
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if ($previous !== null && $previous < $current) {
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++$increases;
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}
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$previous = $current;
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}
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return $increases;
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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 $data): int
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{
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$previousSum = null;
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$increases = 0;
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/**
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* @var int $index
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* @var int $indexValue
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*/
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foreach ($data as $index => $indexValue) {
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// If no 'next' indexes are available, skip.
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if (!isset($data[$index + 1], $data[$index + 2])) {
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continue;
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}
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// Calculate the sum of the current value and the next two.
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$newSum = $indexValue + (int) $data[$index + 1] + (int) $data[$index + 2];
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if ($previousSum !== null && $previousSum < $newSum) {
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++$increases;
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}
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$previousSum = $newSum;
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}
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return $increases;
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}
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}
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