Brilliant, yet simple technical questions, can be used for work interview

Few days ago, a friend of mine, sent me set of demonstration questions for 11th grade computer science students from Russia. I throw eye on this exam and decided to use some of those questions to test candidates in my company for hardware engineer position (we’re looking for). If you’re good candidate for this position, you should be able to answer all those questions without even think a minute.

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Following those questions:

Automatic system recoded informational message in Russian from Unicode (16-bit) into KOI-8 (8 bit). After recoding the length of the message decreased by 480 bits. What was the length of the original message in characters?
1) 30          2) 60          3) 120          4) 480

There are 119 participants in bicycle race. Special designed system registers cyclers passing waypoint by writing his serial number with minimum possible number of bits. What will be the size of temporary message, recorded by the system after 70 cyclers passed the waypoint?
1) 70 bits          2) 70 bytes          3) 490 bits          4) 119 bytes

а=D716, b=3318. What the value of c if a<c<b?
1) 11011001          2) 11011100          3) 11010111          4) 11011000

Please calculate 438+5616?
1) 1218 2) 1718 3) 6916 4) 10000012

What logical expression equals to: & !( !B | C ), while &: logical AND, !: logical NOT and |:logical OR
1) !A | !B | !C          2) A & !B & !C          3) A & B & !C          4) A & !B &C

F is a result of logical expression execution with arguments A, B and C

A B C F
1 0 0 1
0 0 0 1
1 1 1 0

What is the expression for F?
1) !A & !B & !C          2) A & B & C         3) A | B | C         4) !A | !B | !C

For encoding characters A, B, C and D we decided to use two bits numbers sequence (from 00 to 11). What was the result of coding sequence BACD on base 16?
1) 4A          2) 411          3) BACD          4) 1023

Led table contains of number of leds. Each led can be in one of following states: “On”, “Off”, “Blinking”. What is the minimal number of leds should be on table in order to display 18 difference signals?

Please calculate 2514 + 11-4 – 2110?

To calculator there are only two commands 1: “add 3”, 2: “multiply by 4”. Please write down the sequence of the calculator command in order to convert number 3 to number 57 while using not more, then 6 commands. For example to convert 2 into 50 you should write following: “21211” (X4,+3,X4,+3,+3)

The speed of data transfer over network is 128000 bits/sec. Please calculate the time (in seconds) will take to transfer 625 kBytes in this network.

Write a simple program (by using your favorite programming language) to convert the array of 30 integers into array of modulus of items from input array without using modulus calculation special function.


Good luck!

For people, currently employed in my company (hardware devs) it took less, then10 minutes to solve all those questions. However, I was shocked, that at least half of new candidates, come to interview failed to solve it.

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13 Responses to “Brilliant, yet simple technical questions, can be used for work interview”

  1. anonymous Says:

    Sorry, but at least two of those questions are just broken.

    a < c < b
    a = 0xD7 = -41
    b = 0×39 = 57

    Which means we are talking about 8 bits signed. Which means options become: -39, -36, -41, -40 which in turn means c can be -39, -36 or -40.

    Another one:

    BACD = 01001011 = 0×4D which is not offered.

  2. Tamir Says:

    You right, it should be 331~8, not 33~18. My fault :)

  3. anonymous Says:

    “For people, currently employed in my company (hardware devs) it took less, then10 minutes to solve all those questions. However, I was shocked, that at least half of new candidates, come to interview failed to solve it.”

    “You right, it should be 331~8, not 33~18. My fault”

    Should you all be fired!!!!

  4. CS types take themselves too seriously Says:

    Before you look down your nose at those who cannot solve your math problems, you should possibly look into the proper use of commas. See corrected quote below. (Only one was corrected as there are way too many grammatical errors on this page to correct.)

    “For people currently employed in my company (hardware devs), it took less than 10 minutes to solve all those questions. However, I was shocked that at least half of new candidates who come to interview failed to solve it.”

  5. CS types take themselves too seriously Says:

    LOL,

    I missed like 3 more errors in your quote. Damn!

  6. Tamir Says:

    Yap. I have some problems with English grammar, but I’m working on it :)

  7. Khanino Says:

    Solving these questions does not proved anything, except that you did well in theoretical courses. While in school I knew a lot gals that were genius in theoretical stuff, but fail miserable when it come to do higher level programming projects like concurrency,cryptography.

  8. peter Says:

    If you were to ask me any of those questions at an interview I would walk out.

    The reason why: I’m dyslexic, I struggle to perform mental arithmatic and especially so under pressure.

    But being dyslexic doesn’t stop me from being a damn good developer, it just means I have to get better specifications which display the calculations! or alternatively not go down to such a low level, when it’s not necessary.

  9. Tamir Says:

    Peter,
    All those questions can be asked also verbally and have nothing with mental math.
    I’m sure, that you’re a good programmer, however I have two programmers, who have APD and dysgraphia. Me, personally, have phoneticized spelling (as you can see in this blog), but I’m good with it :)

  10. peter Says:

    Spoken like someone to whom math comes easily.

    q1. Math
    q2. Math
    q3. Math
    ….

    There is only a few questions there which don’t involve math, written or mental.

    The .Net framework hides a lot of math and binary information from the developer.

    I find questioning like this to be the equivalent of Red Brick university snobbery.

    i.e. if your degree isn’t from a red brick university then it isn’t a true degree.

    if you can’t do the math you can’t be a programmer? is a false statement.

    I don’t know the mechanics of my car engine but I can use it.

    Admittedly if the role is heavily math based then some warning up front would be required on the job posting which would deter the likes of me.

  11. Jeff Says:

    question 2: There are 119 participants in bicycle race. Special designed system registers cyclers passing waypoint by writing his serial number with minimum possible number of bits. What will be the size of temporary message, recorded by the system after 70 cyclers passed the waypoint?

    best answer is to use a bit mask, one bit per cycler. Your message is always 119 bits.

  12. TopDev Says:

    If I was to be given these questions at an interview I’d just walk out.

    Such stupid questions, they really are, they prove nothing.

  13. Aaron Says:

    when i was hiring some devs for a networking prj. I asked like
    ushort a = 2;
    ushort b = 6;
    please switch the value of a and b w/o extra variables or memory.(If someone make it, i will ask her/him to consider overflow)

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