46 lines
1.0 KiB
PHP
46 lines
1.0 KiB
PHP
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<?php
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/*
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* This file is part of Respect/Validation.
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*
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* (c) Alexandre Gomes Gaigalas <alexandre@gaigalas.net>
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*
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* For the full copyright and license information, please view the LICENSE file
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* that was distributed with this source code.
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*/
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declare(strict_types=1);
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namespace Respect\Validation\Rules;
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use function is_numeric;
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/**
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* Validates whether the input follows the Fibonacci integer sequence.
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*
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* @author Danilo Correa <danilosilva87@gmail.com>
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* @author Henrique Moody <henriquemoody@gmail.com>
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* @author Samuel Heinzmann <samuel.heinzmann@swisscom.com>
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*/
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final class Fibonacci extends AbstractRule
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{
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/**
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* {@inheritDoc}
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*/
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public function validate($input): bool
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{
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if (!is_numeric($input)) {
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return false;
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}
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$sequence = [0, 1];
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$position = 1;
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while ($input > $sequence[$position]) {
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++$position;
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$sequence[$position] = $sequence[$position - 1] + $sequence[$position - 2];
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}
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return $sequence[$position] === (int) $input;
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}
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}
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