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  1. <?php
  2.  
  3. /**
  4.  * Project Euler Problem 3: Largest prime factor
  5.  * 
  6.  * The prime factors of 13195 are 5, 7, 13 and 29.
  7.  * 
  8.  * What is the largest prime factor of the number 600851475143 ?
  9.  * 
  10.  * Problem: https://p...content-available-to-author-only...r.net/problem=3
  11.  * Solution: https://g...content-available-to-author-only...b.com/potherca-blog/ProjectEuler/blob/master/src/PHP/Solutions/Problem003.php
  12.  * Live code: https://i...content-available-to-author-only...e.com/O2tMUJ
  13.  */
  14. namespace Potherca\ProjectEuler\Solutions\Problem003
  15. {
  16.     use Potherca\ProjectEuler\Calculators\PrimeFactorCalculator as Calculator;
  17.  
  18.     $number = 600851475143;
  19.  
  20.     $solution = (new Calculator())->getLargestPrimeFactor($number);
  21.  
  22.     echo $solution;
  23. }
  24.  
  25. namespace Potherca\ProjectEuler\Calculators
  26. {
  27.     class PrimeFactorCalculator
  28.     {
  29.         final public function getPrimeFactors(int $subject): array
  30.         {
  31.             $factors = [];
  32.  
  33.             $currentPrime = 2;
  34.  
  35.             $limit = gmp_strval(gmp_sqrt($subject));
  36.  
  37.             while ($currentPrime < $limit) {
  38.             	if ($subject % $currentPrime === 0) {
  39.             		$factors[] = $currentPrime;
  40.             	}
  41.             	$currentPrime = gmp_strval(gmp_nextprime($currentPrime));
  42.             }
  43.  
  44.             return $factors;
  45.         }
  46.  
  47.         final public function getLargestPrimeFactor(int $subject): int
  48.         {
  49.         	return end($this->getPrimeFactors($subject));
  50.         }
  51.     }
  52. }
  53.  
Success #stdin #stdout #stderr 0.8s 24616KB
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PHP Notice:  Only variables should be passed by reference in /home/LxTty9/prog.php on line 49
https://ideone.com/O2tMUJ
Solution in PHP for Project Euler Problem 003
language:
PHP (php 7.3.5)
created:
4 years ago
visibility:
public

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