What is the largest prime factor of the number...
Hello
I am taking part in the Euler Project, one of the problems is as follows:
"The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 317584931803?"
Now, I wrote a program that can do this. However, the problem arises with the number 317584931803. I realised that I cannot use long, int, byte or even float declarations with this number. I was told to use a class called "BigInteger".
Well, I modified my program according to this. And I wrote the following code...I know the code works, but there is one huge big problem.... IT TAKES FOREVER TO COMPUTE!
heck! forget 317584931803, instead I used 15 and its still computing! Its been 5 mins already! Maybe its got caught in some infinite loop, but I doubt that...
[code]
import java.math.*;
public class euler6 {
static BigInteger a[]=new BigInteger[999];
static int j=0;
static BigInteger bi = new BigInteger("15"); //This is the number whos largest prime factor you have to find.
static BigInteger i=new BigInteger("2");
static final BigInteger one=new BigInteger("1");
public static void main (String arhs[]){
for(;i.compareTo(bi)==-1;i.add(one))
if ((bi.mod(i).equals("0"))&& (findPrime(i)))
{a[j]=i;
j++;}
for(int f=0;f<a.length;f++)
System.out.print(a[f]+" ");
}
public static boolean findPrime(BigInteger n){
BigInteger x=new BigInteger("2");
for(;x.compareTo(n)==-1;x.add(one))
if (n.mod(x).equals("0"))
return false;
return true;
}
}>
