Background Information
We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++.
The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence.
Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test.
After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs)
My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question.
The Question
There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j.
class C
{
public:
int foo() {...}
int boo() {...}
int boo_and_foo() {...}
int foo_and_boo() {...}
};
In code one might write:
C c;
.
.
int i = c.foo() + c.boo();
But it would be better to have:
int i = c.foo_and_boo();
What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter.
Note that foo and boo are not commutative.
Possible Solution
We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail.
We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more.
Is this really a difficult question?
Should it be removed?
Or are we just not seeing the right candidates?
