The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.

73167176531330624919225119674426574742355349194934

96983520312774506326239578318016984801869478851843

85861560789112949495459501737958331952853208805511

12540698747158523863050715693290963295227443043557

66896648950445244523161731856403098711121722383113

62229893423380308135336276614282806444486645238749

30358907296290491560440772390713810515859307960866

70172427121883998797908792274921901699720888093776

65727333001053367881220235421809751254540594752243

52584907711670556013604839586446706324415722155397

53697817977846174064955149290862569321978468622482

83972241375657056057490261407972968652414535100474

82166370484403199890008895243450658541227588666881

16427171479924442928230863465674813919123162824586

17866458359124566529476545682848912883142607690042

24219022671055626321111109370544217506941658960408

07198403850962455444362981230987879927244284909188

84580156166097919133875499200524063689912560717606

05886116467109405077541002256983155200055935729725

71636269561882670428252483600823257530420752963450

Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?

– Project Euler Problem 8

WTF?

function getLargestProduct(digitsInNumber::Array{UInt8,1}, numberOfProducts::UInt64)
        productMax::UInt64 = 0;
        sequenceOfDigits = Array{UInt8,1}();
        i::UInt64 = 1;
        while i+numberOfProducts <= length(digitsInNumber)
                digits::Array{UInt8,1} = digitsInNumber[i:i+numberOfProducts-1];
                product::UInt64 = prod(digits);
                if product > productMax
                        productMax = product;
                        sequenceOfDigits = digits;
                end
                i+= 1;
        end
        return productMax, sequenceOfDigits
end




function parseARGS()
        if isempty(ARGS)
                numberOfProducts::UInt64 = 13;
        else
                numberOfProducts = tryparse(UInt64,ARGS[1]);
        end
        return numberOfProducts
end


function main()
        number::BigInt = 7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450;
        digitsInNumber::Array{UInt8,1} = digits(number);
        numberOfProducts = parseARGS();
        largestProduct, sequenceOfDigits = getLargestProduct(digitsInNumber, numberOfProducts);
        println(largestProduct);
        for i in sequenceOfDigits[1:end-1]
                print(i,"x");
        end
        print(sequenceOfDigits[end]);
end

main()


$ julia ProjectEuler0008.jl 4
5832
9x8x9x9  0.000812 seconds (10.02 k allocations: 459.828 KiB)

$ julia ProjectEuler0008.jl 5
40824
9x7x8x9x9  0.000905 seconds (10.03 k allocations: 460.281 KiB)

$ julia ProjectEuler0008.jl 13
23514624000
5x9x8x4x6x6x9x8x6x6x7x5x5  0.000930 seconds (10.06 k allocations: 460.781 KiB)

$ julia ProjectEuler0008.jl 50
17371650400163201024
8x2x8x6x5x4x5x6x7x4x9x2x5x6x6x5x4x2x1x9x5x3x8x5x4x6x6x8x7x1x6x8x5x4x2x8x2x6x1x3x2x1x9x1x9x3x1x8x4x7  0.001201 seconds (10.21 k allocations: 508.859 KiB)