Game programming test(Interview test)

hybrid · Post by **hybrid** » Thu Mar 27, 2008 9:40 am

Ok, this is my solution to the TISC question:
STO A,1 -- Write register a to mem 1
SUB A,0 -- Set register a to ('a-$0)
SUB A,1 -- Set register a to ('a-$0)-$1=='a-$0-'a==$0
STO A,1 -- Write register a (which is now $0) to mem 1

Note that 'a in the comments is the inital value of register a, it's not the updated value. So this should work as expected, with only one register and 4 instructions.

Dorth · Post by **Dorth** » Thu Mar 27, 2008 10:24 am

Well, my roommate solution was only one register too, but I don,t see a case where yours doesn't work. Nice. I didn't touch the problem at all for that matter, just sent my roommate answer to Halifax for confirmation, that's all.

I can see something like that in a test. And while that solution, if no problem arise IS better, if the question asked for the solution in 7 steps (which is unclear in Halifax post), I know some places that would actually see it as only a partial answer because it does not meet the criteria. Giving both answer might give bonus points on the other hand. No matter, I'm interested to know if Hybrid's answer can be wrong in some context. I don't think so, but I'd like to know

MasterGod · Post by **MasterGod** » Thu Mar 27, 2008 12:27 pm

I had such tests when I was qualifying to some unit in the army (haven't joined yet) and they said that you must not pass X lines with your answer though the answer can be X or less lines and passing the X-th line just make you loose some points but doesn't cancel your answer completely.

hybrid · Post by **hybrid** » Thu Mar 27, 2008 3:26 pm

Haha, you can also repeat the last line until 7 statements are done

Dorth · Post by **Dorth** » Thu Mar 27, 2008 5:46 pm

Indeed. I did a smarty pant answer like that once in an interview and the interviewer was half-laughing for the next 5 minutes ^^
I received an offer that time

Halifax · Post by **Halifax** » Thu Mar 27, 2008 7:56 pm

hybrid wrote:Ok, this is my solution to the TISC question:
STO A,1 -- Write register a to mem 1
SUB A,0 -- Set register a to ('a-$0)
SUB A,1 -- Set register a to ('a-$0)-$1=='a-$0-'a==$0
STO A,1 -- Write register a (which is now $0) to mem 1

Note that 'a in the comments is the inital value of register a, it's not the updated value. So this should work as expected, with only one register and 4 instructions.

If my test case serves me correct, that doesn't work. The value swapped to $1 is negative $0:

Code: Select all

$0 - 24
$1 - 31
A - 12
B - 15

STO A,1 ($1 = 12)
SUB A,0 (A - $0 = 12 - 24 = -12)
SUB A,1 (A - $1 = -12 - 12 = -24)
STO A,1 ($1 = -24)

$1 = -24

Remember that the value of A, B, $0, and $1 are all random when the system starts up.

hybrid · Post by **hybrid** » Thu Mar 27, 2008 8:05 pm

Hmm, you're right. I also wrote that in my comment

Halifax · Post by **Halifax** » Thu Mar 27, 2008 8:26 pm

If only TISC had a NEG <register> command.

Then it would be the best processor out there.

MasterGod · Post by **MasterGod** » Thu Mar 27, 2008 8:28 pm

ROFL!! At first I read it as NGE..