Interview Technical Test Preparation

[jillduffy]

See also "Game Programming Tests."

[jwalters]

I just wanted to thank everyone for responding with your technical test/interview insights! This is a huge help to me and definitely helps me to see where I need to fill in the gaps in my knowledge. Thanks a ton!!!

[Claxon]

This is one that we used to use in my office (it isn't in use any more though so don't expect to get this test if you apply here) to programmers applying for a J2me programming role.

Part 1 / Multiple choice Score: [ __ / 24 ]

6 Questions, 4 points each.
Instructions: Select the most accurate answer(s) for each question.

1. Which of the following are FIFO data structures?
a. Stack
b. Queue
c. Tree
d. Vector
e. None of the above

2. Which of the following keywords are valid in Java (as of Java 1.4)?
a. visible
b. final
c. synchronized
d. temporary
e. All of the above

3. Which of the following can be used to improve performance of 3D graphics on mobile devices?
a. Multiple light sources
b. LOD (Level Of Detail)
c. Occlusion culling
d. Ray-tracing
e. None of the above

4. When we say “big endian”, we mean that
a. The function has a return value.
b. The function does not have a return value.
c. It begins with the most significant byte.
d. It ends with the most significant byte.
e. None of the above

5. Which of the following are considered ‘object-oriented’ programming languages?
a. XML
b. C
c. C++
d. Visual Basic
e. Smalltalk

6. A Java ‘interface’ has the following characteristics:
a. It can extend one or more other interfaces.
b. It can have implementations for some or all of its methods.
c. It cannot contain variables.
d. It can have a user-defined constructor.
e. All of the above.


Part 2 / Short answers Score [ __ / 40 ]

8 Questions, 5 points each.
Instructions: Answer each of the following questions using one or more sentences.

1. Define the following terms:
a. Encapsulation
b. Multiple Inheritance
c. UML
d. Unit Testing
e. Abstract Class

2. What are the differences between ‘private’, ‘protected’ and ‘public’ in Java? Where can you use these keywords?
3. What is the Singleton pattern? When would you use it?
4. Describe the Pythagorean theorem, and give an example of how it might be used in game programming.
5. In regards to 3D graphics, what is the difference between world, view and screen coordinates?
6. How can you find out the normal vector of a triangle in 3D space?
7. What is alpha blending?
8. What kind of techniques/tools would you use to tune performance bottlenecks of a mobile game?


Part 3 / Programming Score [ __ / 36 ]

3 Questions, 12 points each.
Instructions: complete the following examples by adding the source code in Java

1. Using either Java or C/C++, write a method to sort an array of integers. Value clarity over algorithm efficiency. Assume that the input data is a valid array of 32-bit integers.

example in Java:

void sortArray(int[] array)
{
	// your code here
} 

example in C:
void sortArray(int* array, int array_size)
{
	// your code here
}

2. Assuming you are working on a platform that does not support floating point operations, write functions that perform the following operations on 32-bit signed fixed point integer variables with 16 bits for the fractional parts (= 16.16 fixed point). The return values should be in the same format. You can use either Java or C/C++.

a. Addition (a+b)
b. Multiplication (a*b)
c. Division (a/b)

example:

int add_fp_16_16(int a,	int b)
{
	// your code here
}

int mul_fp_16_16(int a, int b)
{
	// your code here
}

int div_fp_16_16(int a, int b)
{
	// your code here
}

3. The following code segment implements an endless loop that checks the current key status (of all keys, where each key has a specific bit position) to see if the key KEY_FIRE has been pressed, and if so take appropriate action. A key’s bit is automatically set to one (1) while pressed, and zero (0) when not pressed. Complete the C/C++ or Java code such that it takes action only when the key is first pressed.

int KEY_FIRE = 0x1;  // constant value; bit position of key
int key, past = 0;

while(true)
{
	key = getKey();

	if(____________________________________)  // fill in this space
	{
		// Take action if KEY_FIRE was just pressed.
		// …
	}
	past = key;
}

As you can see it's divided into 3 sections of varying difficulty. Applicants would have to fill out this test on paper, so no compiler to test for syntax errors. As you can see there is a range of questions, that don't necessarily apply to j2me programming.

The way we issued the test was to give the applicant the sheets of paper with these questions, and leave them in a room for 30 minutes - 45 minutes too fill it out. Once they had finished (we didn't set a time limit, but many people felt compelled to stop after 45 minutes whether they had anwered all of the questions or not), one of us would sit with them and go through the questions and their answers. If they got it right, we'd quickly move on to the next. If they got it wrong, missed it out, or only partially correct, we would talk it over with them and try to nudge them in the right direction (any answers they gave at this point didn't count towards their final marks, but it was useful to us to see if they could work out the problem with a little help, or if they simply didn't have a clue).

The average mark for the above test was about 60%, so people often felt bad about their result, when we were quite happy with it. What we really looked for was how well they worked through the answers to the questions with us at the end, and whether they seemed to have a good grasp of the concepts.

[jwalters]

Thanks Claxon! It's always great to get another example test to work from.