Re: What's the best language to start with

Re: What's the best language to start with

[Tim Behrendsen]

On Sat, 10 Aug 1996, DAVID A MOLNAR wrote:

> In article <01bb8540$59ac8420$87ee6fce@timpent.airshields.com> you wrote:
> : I should say that my test had them render solutions in C.  I
> : gave them a moderately easy but not trivial algorithm to
> : implement, and they just plain couldn't do it.
> 	I'm not a CS grad, but I can't help wondering what is considered 
> a moderately simple algorithm at this level.  What sort of description 
> would you give to a person in that position? I would imagine that a fair 
> level of mathmatical literacy might be expected, not to mention some 
> acquaintance with the field you are hiring for...
> 	May I respectfully ask what kind of an algorithm it is/was? If 
> you're still using it as a test for job applicants, I understand if you 
> don't wish to disclose the particulars. I only ask because I am currently 
> finishing up a CS1/CS2 sequence and have been following this debate with 
> increasing interest. Although I can't help but wonder why no one has yet 
> mentioned Scheme (my own 'first'). :-) It's caused me to take a look at 
> what I have and have not learned in the year or so that I've been taking 
> classes...and what I need to learn in the future. Fortunately, I have 
> some years yet until graduating from college. :-)

I have been intentionally not giving my problems away, because it's hard
to think of good solid problems that can be solved in a reasonable amount
of time that doesn't get too much into specialized knowledge that
would make them unfair.  Basically, I have a problem that is arithmetic
oriented, to see if someone can think mathemetically; a logic problem
to see if they understand bits and logic; stuff like that.

I will tell you one "bonus" problem that I give to see if they
are paying attention; I don't really factor it in much when I decide to
hire someone or not because it's not really a fair question.  I love
the problem, though, because it's a pure "thinking" problem.

----
You are writing a preprocessor program that takes C source as
its input.  The preprocessor replaces all variables and symbols
in the program with unique names of the form VARxxxxxx, where
"xxxxxx" is an incrementing decimal number.  Describe what is
needed to handle the case where the input source file already
contains a variable of that form.
----

I would say about 95-98% of the applicants get this question
wrong.  I have had people I respect give the "obvious" wrong answer,
though, so it's mostly a matter of not really thinking about it
before answering.

You should see some of the answers I get that are WAY off,
though.  It's really scary.  At least 20% of the answers are
some form of "I've never done a C preprocessor before, so I
don't know." Yes, these are people with full-blown degrees.

-- Tim Behrendsen (tim@airshields.com)

Hiring tests (Re: What's the best language to start with)

[Ray Blaak]

On Sat, 10 Aug 1996, DAVID A MOLNAR wrote:
> 	May I respectfully ask what kind of an algorithm it is/was? If 
> you're still using it as a test for job applicants, I understand if you 
> don't wish to disclose the particulars.

I used to work for one company that had a programming test about artificial
vision -- find the blobs. Sounded frightful until I realized it was just a
floodfill algorithm. Apparently it used to upset a lot of applicants.

Cheers,
Ray Blaak
blaak@mda.ca

Re: What's the best language to start with

[Frank Manning]

In article <Pine.A32.3.91.960811134122.76393A-100000@wc.airshields.com>
Tim Behrendsen <tim@airshields.com> writes:

  [ Bonus interview question ]

----
> You are writing a preprocessor program that takes C source as
> its input.  The preprocessor replaces all variables and symbols
> in the program with unique names of the form VARxxxxxx, where
> "xxxxxx" is an incrementing decimal number.  Describe what is
> needed to handle the case where the input source file already
> contains a variable of that form.
----

OK, I'll bite. I'd say that particular case is handled just like any
other case. The input variable/symbol is a completely separate entity
from output string "VARxxxxxx" you replace it with, except for the
1:1 mapping of input vs. output strings. Examples:

   INPUT          OUTPUT

   abc            VAR000001
   Color_Value    VAR000002
   VAR000001      VAR000003
   VAR000004      VAR000004
   X_Prime        VAR000005

Nah...that was too easy. I musta missed something...

-- Frank Manning

Re: What's the best language to start with

[Tim Behrendsen]

Frank Manning <frank@bigdog.engr.arizona.edu> wrote in article
<4up0ar$pim@news.ccit.arizona.edu>...
> In article <Pine.A32.3.91.960811134122.76393A-100000@wc.airshields.com>
> Tim Behrendsen <tim@airshields.com> writes:
> 
>   [ Bonus interview question ]
> 
> ----
> > You are writing a preprocessor program that takes C source as
> > its input.  The preprocessor replaces all variables and symbols
> > in the program with unique names of the form VARxxxxxx, where
> > "xxxxxx" is an incrementing decimal number.  Describe what is
> > needed to handle the case where the input source file already
> > contains a variable of that form.
> ----
> 
> OK, I'll bite. I'd say that particular case is handled just like any
> other case. The input variable/symbol is a completely separate entity
> from output string "VARxxxxxx" you replace it with, except for the
> 1:1 mapping of input vs. output strings. Examples:
> 
>    INPUT          OUTPUT
> 
>    abc            VAR000001
>    Color_Value    VAR000002
>    VAR000001      VAR000003
>    VAR000004      VAR000004
>    X_Prime        VAR000005
> 
> Nah...that was too easy. I musta missed something...

Nope, you got it. :)

The typical wrong answer (when they make an answer at
all) is to start describing a list they keep of the ones that
are already of the form, etc.  Occasionally I'll get someone
go off the deep end and describe incredibly elaborate data
structures.  Heh heh.

I don't count it too much, because it's so stacked to lead
the person down the wrong path.  "Trick" questions rarely
tell you anything significant, except where the "wrong"
answer is really confused.

-- Tim Behrendsen (tim@airshields.com)

Re: What's the best language to start with

[Bob Kitzberger]

Tim Behrendsen (tim@airshields.com) wrote:

> You are writing a preprocessor program that takes C source as
> its input.  The preprocessor replaces all variables and symbols
> in the program with unique names of the form VARxxxxxx, where
> "xxxxxx" is an incrementing decimal number.  Describe what is
> needed to handle the case where the input source file already
> contains a variable of that form.

Do they get extra credit if they hand-optimize to take into
account paging locality, compiler optimizations, etc.?

	:-)


--
Bob Kitzberger	      Rational Software Corporation       rlk@rational.com
http://www.rational.com http://www.rational.com/pst/products/testmate.html

Re: What's the best language to start with

[Robert Dewar]

Tim says

"I would say about 95-98% of the applicants get this question
wrong.  I have had people I respect give the "obvious" wrong answer,
though, so it's mostly a matter of not really thinking about it
before answering."

I can't see an obviously wrong answer, only a trivially right one, so
perhaps you should tell us the mysterious obviously wrong answer. I tried
this on a few people around here and they were all as puzzled as I was.

Re: What's the best language to start with

[Tim Behrendsen]

Robert Dewar <dewar@cs.nyu.edu> wrote in article
<dewar.840032915@schonberg>...
> Tim says
> 
> "I would say about 95-98% of the applicants get this question
> wrong.  I have had people I respect give the "obvious" wrong answer,
> though, so it's mostly a matter of not really thinking about it
> before answering."
> 
> I can't see an obviously wrong answer, only a trivially right one, so
> perhaps you should tell us the mysterious obviously wrong answer. I tried
> this on a few people around here and they were all as puzzled as I was.

Well, it seemed obvious to me, too when I heard it the first time
(A friend of mine's father used it as an intelligence test to
programmers), but I guess that shows the general level of
competence in the world.

The typical wrong answer (if I get an answer at all) is to describe
some elaborate data structure to keep track of the "duplicates".
Here's a couple of examples [pulling off the "reject" stack]:

-----------
"The basic need for the program is to replace the input, given
from a C source, with a unique name of "VARXXXXX".

The main body of this program would simply read in data (in c)
and replace it with a variable name.  In order to make sure any
one input source did not have the same variable name (as what it
might be replaced with) we would simply have to add a condition
to our loop.  The program would be set up in the form of a _loop_
where a variable is read _AND_ check that the unique name it will
be replaced with is not the same as the input source file and
then proceed to replace the variables.  In the case where the
input file did have the same variable, a new variable name would
have to be used."  [Underlines were the applicant's]

-------------------
- or -

"I guess it depends on the requirements, performance, but you
could read the code first, save all the variables in a list,
then read the code a second time, then you replace the variable
to a new name, you can check to see if exists already."

Without mentioning the school, this last graduated with a 3.5
and a Dean's Honor List distinction.  Completely unable to
think.
---------------------
I wasn't intentionally picking the most lame ones, BTW; these
were pretty much the ones on the top of the (reject) stack.

Also to be fair, I make them hand-write the solutions, which
is why the grammar is often not perfect (although, still
pretty lame).

-- Tim Behrendsen (tim@airshields.com)