CODEWITHSUNDEEP
javaproject
Kyle
Kyle

Reputation: 11

Project Euler #10 Java not working

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

            public class Problem10
            {
                public static void main(String[] args)
                {
                    int sum = 17;
                    for(long i=11; i<2000000; i+=2)
                    {
                        if(isPrime(i)) sum += i;
                    }
                    System.out.println(sum);    

                }

                public static boolean isPrime(long n)
                {
                    if(n==2) return true;
                    if(n%2 == 0) return false;
                    for(long i=3; i<= Math.sqrt(n); i+=2)
                    {
                        if(n%i == 0) return false;
                    }
                    return true;
                }
            }

I don't see what is wrong with this. It keeps printing 1179908154 which is incorrect.

Upvotes: 0

Views: 104

Answers (1)

rgettman
rgettman

Reputation: 178263

Your sum is an int, but integer overflow is occurring. If you change the datatype to long, then the answer changes to 142913828922, which is longer than the maximum possible int. That appears to be the correct answer.

Upvotes: 3

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