Project Euler - Problem 10

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

Find the sum of all the primes below two million.

– Project Euler Problem 10

I really should start looking for alternatives to brute-forcing prime detection. Perhaps something iterative as prime decomposition to avoid too much checking. Perhaps next time… ;)

function isPrime(n::UInt64)
        isPrimeNumber::Bool = true;
        if n%2 == 0
                isPrimeNumber = false;
                return isPrimeNumber
        end
        for i in 3:2:(n-1)
                if n%i == 0
                        isPrimeNumber = false;
                        return isPrimeNumber
                end
        end
        return isPrimeNumber
end

function sumOfPrimesBelowThreshold(N::UInt64)
        sumOfPrimes::UInt64 = 0;
        if N >= 2
                sumOfPrimes = 2;
        end     
        currentNumber::UInt64 = 3
        while currentNumber < N
                if isPrime(currentNumber)
                        sumOfPrimes += currentNumber;
                end     
                currentNumber += 2;
        end     
        return sumOfPrimes
end 

function parseARGS()
        if isempty(ARGS)
                N::UInt64 = 2000000;
        else    
                N = tryparse(UInt64,ARGS[1]);
        end
        return N
end

function main()
        N::UInt64 = parseARGS();
        sumOfPrimes = sumOfPrimesBelowThreshold(N);
        println(sumOfPrimes);
end

main()

$ julia ProjectEuler0010.jl 10
17
  0.000040 seconds (17 allocations: 912 bytes)

$ julia ProjectEuler0010.jl 100
1060
  0.000042 seconds (19 allocations: 944 bytes)

$ julia ProjectEuler0010.jl 1000
76127
  0.000221 seconds (19 allocations: 944 bytes)

$ julia ProjectEuler0010.jl 2000000
142913828922
  323.662743 seconds (19 allocations: 944 bytes)

There has to be a faster way for this.