projecteuler.net第三题

http://projecteuler.net/index.php?section=problems&id=3
projecteuler.net第三题
The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?

找出600851475143的最大质因数？

评论

2 楼 wenyiyun 2009-11-03  

require 'mathn'
class Integer
def prime_factors
x = self
prime_gen = Prime.new
factors = prime_gen.each do |prime|
(puts prime || [] << prime) if x % prime == 0
end
puts "the prime factors of #{self} #{factors}"
end
end

1 楼 lampeter123 2009-07-08  

第三题答案：6857
public class Problem_3{  
    public static void main(String[] args){  
        long num = 600851475143L;  
        long prm = 2;  
        while(prm != num){  
            if(num%prm == 0) num /= prm;  
            else             prm += 1;  
        }  
        System.out.println(prm);  
    }  
}