Project Euler – Problem 3 Solution

Question: The prime factors of the number 13195 are 5, 7, 13, and 29. What is the largest prime factor of the number 600851475143?

* https://projecteuler.net/problem=3

Php;

number = $this->original_number = $number; } /** * Finds the next prime number */ private function find_next_prime_number() { if ($this->current_prime_number == 2) { $this->current_prime_number++; } else { $this->current_prime_number += 2; } $can_divide = false; $number = 2; while ($number < $this->current_prime_number) { if ($this->current_prime_number % $number == 0) { $can_divide = true; } $number++; } if ($can_divide) { $this->find_next_prime_number(); } } /** * Finds the prime factors and largest prime factor of given number */ public function find_prime_factors() { while ($this->number > 0) { if ($this->number == 1) { $this->largest_prime_number = $this->current_prime_number; break; } else { if ($this->number % $this->current_prime_number == 0) { $this->prime_numbers[] = $this->current_prime_number; $this->number /= $this->current_prime_number; } else { $this->find_next_prime_number(); } } } echo $this->largest_prime_number; } } $solver = new ProblemSolver(600851475143); $solver->find_prime_factors();

Javascript;

'use strict'; var number = 600851475143, prime_number = 2; function find_next_prime_number() { var can_divide = false; var n = 2; if (prime_number === 2) { prime_number++; } else { prime_number += 2; } while (n < prime_number) { if (prime_number % n === 0) { life_divide = true; }n++; } if (can_divide) { find_next_prime_number(); } } while (number > 1) { if (number % prime_number === 0) { number /= prime_number; } else { find_next_prime_number(); } } console.log(prime_number);