Finding Largest Prime Number Out of 600851475143

How to find largest prime factor of 600851475143 in java

How about this solution:

public static long factor(long rc) {

   long n = rc;

   List<Long> pfactors = new ArrayList<Long>();

    for (long i = 2 ; i <= n ;  i++) {

        while (n % i == 0) {
            pfactors.add(i);

            n = n / i;

        }

    }

    return pfactors.get(pfactors.size() - 1);
}

Runs fast for me.

Find largest prime factor for the number 600851475143L

try this solution :

public class LargestPrimeFactor 
{

    public static int largestPrimeFactor(long number) {
        int i;

        for (i = 2; i <= number; i++) {
            if (number % i == 0) {
                number /= i;
                i--;
            }
        }

        return i;
    }

    public static void main(String[] args) {
        System.out.println(LargestPrimeFactor.largestPrimeFactor(600851475143l));
    }

}

The problem was because you have nested loop with very big number, and that what made the loop

Greatest Prime Factor

let primeFactor = x => {    if (x === 1 || x === 2) {        return x;    }
    while (x % 2 === 0) {        x /= 2;    }        if (x === 1) {        return 2;    }
    let max = 0;    for (let i = 3; i <= Math.sqrt(x); i += 2) {        while (x % i === 0) {            x /= i;            max = Math.max(i, max);        }    }
    if (x > 2) {        max = Math.max(x, max);    }        return max;};
console.log(primeFactor(35));console.log(primeFactor(13195));console.log(primeFactor(27));console.log(primeFactor(1024));console.log(primeFactor(30974914));console.log(primeFactor(600851475143));

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