Programming test
1) You can use any of the following languages: c++, c#, java, PHP, javascript to
answer the questions
 Data structures
1) Define a node of a binary tree.
2) How can you store a graph (V, E), where V is the set of vertices and E is
the set of edges, in a data structure?
3) Reverse the order of the contents of a queue. For example, if the queue
has 1,2,3,4 change it to 4,3,2,1. You do not need to write any code for this,
just the logic/algorithm.
 Using a vector/list.
a) Declare a vector/list, which will store integers.
b) Insert 10 random integers into the vector/list. The random number
should be -/+ 5 to the second power of the index you are inserting to. For
example if you are inserting at position 5, your random number should be
in the range [5^2 – 5, 5^2 + 5].
c) After your insertion process is complete, you have to randomly shuffle
the vector/list.
d) Lastly, delete the smallest number in the vector/list.
e) Assume you have the following statements and functions:
1) vector<T> name, list<T> name
2) vector.insert(type value) – inserts value at the next available spot
3) vector.insert(int index, type value) – inserts value at the given index
4) void srand(int) – seed random number generator
5) int rand() – returns a random number
6) vectors/lists have overloaded assignment(=) operator
7) vector.remove(int index) – index to be deleted from
8) assume all functions for vector<t> are present in list<T>
 moving images in a loop, pixels and size awareness
a) Assume you have a function draw(image img, point position,rect
rectangle). It takes three parameters: the image to be drawn, the position
on the screen it will be drawn to in pixels, and the rectangle representing
the image.
b) The screen size of all displays is in pixels(integer), (screen-width, screenheight). The width X height is basically the resolution of the phone. For
example, the resolution of iphone 4 is 640x960. So the screen width is
640 pixels and the screen height is 960 pixels.
c) The point is a struct, with two data members; x and y. x denoted the
position on the x axis and y denoted the position on the y axis. If you draw
an image on point (0,0), it will be drawn on the origin. The image is
always drawn starting from its top left corner. So, if you draw the image
at point (640,960), you would not see the image on the screen. This is the
declaration of the struct point:
struct point
{
int x,y;
};
this is how a screen looks like.
d) the rect is a struct. Here is the definition of the struct rect:
struct rect
{
int top, left; // top and left corners of the image. Usually 0 if taking the
image from the origin.
int width, height; // width and height of the image
};
e) Your task 1: Assume you have an image ball. The width and height of the
ball are 100x100. You have to draw the ball in the middle of the screen of
resolution 640x960.
Hint: just do not draw at point 320,480. As the image is drawn starting
from its top left corner, do not forget to take its height and width into
account.
f) You task 2: Now assume you have the screen height and screen width
stored in variables screenHeight and screenWidth. You have to draw the
image in the middle of the screen.
g) Your task 3: Assume you have a class game. Put the code to draw the
image in the center in the default constructor of the class game. Do not
worry about decalrig the variables in the constructor. The variables:
image ball, point position, rect rectangle are declared as data member of
the class.
h) Your task 4: Assume you have a function void update() in class game,
which is called in a loop every 20 ms. You task is to move the ball on the
+x axis of the screen starting from the center of the screen. Hint: just
increase the point.x value in the loop.
i) Your task 5: If you just increment the value of poin.x, your ball will go out
of the screen when the point.x value goes beyond the width of the screen.
Now, make the ball turn its direction when it collides with the right wall
(x coordinate screenWidth) and the left wall (x coordinate 0). Hint: keep a
variable direction with two possible values -1 and to denote the direction
of travel on the x axis. Just change the direction when colliding with the
walls.
 Formal logic
1) Give a regex over [a,b]* in which the number of a’s is a multiple of 3.
2) How would you know if a binary number is divisible by 8?
3) Give a DFA over [a]*, which will accept any string other than aaaa.
 SQL Design
1) Give a database diagram to manage an online chat service. You have to
keep information about users, users’ conversations, users’ groups,
messages between 2 people and among groups, and blocked users.
Include information of how the data will be stored.
2) Each user has a name, username, id (auto increment), email, and phone
number
3) A conversation stores information about two people.
4) A group stores information about more than two people.
5) Each message has some text, image link, type (sent/received), read
(true/false), time in Unix time stamp, and id (auto increment)
6) A user cannot send a message to the person who has blocked him.
 SQL Queries: Use any language to mix your queries with variables/conditions
From the diagram you created, write sql queries for the following problems:
1) Get the names of the first 10 users of the service
2) Delete all users who have been blocked by more than 5 people
3) Get names of all users who have had a conversation with username
“hello112”
4) Send a message from user with username “abc” to username “bcd” saying
“hello”
5) Block all users with name “random” from user with username “abc”
6) Get names of the user who have had the highest number of conversations
7) Delete users who have not sent a message since 24 hours
8) User with username “abc” changed his country, which is 2 hours ahead in
time. Change all the times of his received messages.
 OOP Design
1) Consider a game consisting of circles, and squares. If you touch a circle, it
disappears. If you touch a square, its height is doubled. The circles are
moving vertically with a speed of 5 pixels/frame and the squares are
moving horizontally with a speed of 8 pixels/frame. The aim of the game
is the clear out all the circles without touching the squares. If the squares
keep expanding and occupy more than 50% of the screen, the game is
over.
You tasks:
a) Design a class to represent an object (both circle and square).
HINT: keep in mind the variables you used in question 3 to represent
objects.
b) Derive classes circle and square from class object, and add their
properties.
NOTE: I am not looking at how you write the code. I just want to see
how you will design your classes with objects and methods to
represent the objects. I also do not want you to implement the
methods, just declare them. Give them a name that makes sense, and
tells me what it will do.