Dev terms

Question 1

Big O Notation

Answer 1

Defines the performance of an algorithm/system
O 	Complexity 	Rate of growth
O(1) 	constant 	fast
O(log n) 	logarithmic 	
O(n) 	linear time 	
O(n * log n) 	log linear 	
O(n^2) 	quadratic 	
O(n^3) 	cubic 	
O(2^n) 	exponential 	
O(n!) 	factorial 	slow

Question 2

Recursion

Answer 2

Increments n from previous result

Step 1
    If you are at home, stop moving.
Step 2
    Take one step toward home.
Step 3
    "find your way home".

Question 3

Big Data

Answer 3

Big data describes data sets so large and complex that is impossible to manage with conventional data processing tools.

Question 4

Data Structures

Answer 4

Array =
data structure consisting of a collection of elements (values or variables), each identified by at least one array index or key.

Tree =
a hierarchical tree structure, with a root value and subtrees of children with a parent node, represented as a set of linked nodes.

Stack=
collection of elements, with two principal operations:
push, which adds an element to the collection,
AND
pop, which removes the most recently added element that was not yet removed.

Queue=
a collection of entities that are maintained in a sequence and can be modified by the addition of entities at one end of the sequence and removal from the other end of the sequence

Graph
Hash Table=
a structure that can map keys to values.

Linked List =
each node contains: data, and a reference (in other words, a link) to the next node in the sequence.

Heap=
for any given node C, if P is a parent node of C, then the key (the value) of P is greater than or equal to the key of C. In a min heap, the key of P is less than or equal to the key of C.

Question 5

Greedy Algorithm

Answer 5

Picks a selection based on one parameter at the beginning and never reconsiders.
A greedy algorithm picks the best immediate choice and never reconsiders its choices.

Question 6

Hill Climbing

Answer 6

The hill climbing algorithm attempts to find a better solution by generating a neighboring solution. Each neighboring solution is generated based on the best solution so far, with a single element modified.

Question 7

Dynamic Programming

Answer 7

Memoization (yes emoization not memorization), a top-down approach in dynamic programming, which store the results of previous computations for future use.
it refers to simplifying a complicated problem by breaking it down into simpler sub-problems in a recursive manner

Question 8

P vs NP Problem

Answer 8

Finding the original factors of a number is hard. So P is a (polynomial) problem because it is easy to solve. Computer can easily multiply 2 super large numbers without spending significantly more computer time than small numbers.

Q2 is a NP (nondeterministic polynomial) problem because it is easy to verify, but hard to solve.

Question 9

How do computers work?

Answer 9

Abstraction

• Low level = Assembly language, hardware manipulation. Machine language is binary
• Mid level = performance critical software. C, C++
• High level = Ease of use. Python, java, C#

Question 10

Parallelism

Answer 10

Parallelism allows 2 or more tasks to run at the same time,.

Question 11

Race Condition

Answer 11

Output can’t be consistently predicted because dependent on a sequence or timing.
This is what will happen if you allow concurrent transactions in a banking system and race condition isn’t handled.

Question 12

Mutual Exclusion (Mutex)

Answer 12

Now, whenever there’s an ongoing transaction, the system will lock the account(s) involved in the transaction.

Question 13

Semaphore

Answer 13

Binary Semaphore =
2 different states.

Counting Semaphore =
More than 2 states

Question 14

Deadlock

Answer 14

2 oposite transactions crate a deadlock because each transaction blocks its source account.

Question 15

Computer Hacking

Answer 15

Brute-force Attack = A brute-force attack tries every possible passwords, and usually starts by guessing commonly used passwords like “123456”, “abcdef”, etc.
Social Engineering = Social engineering is tricking users into revealing their private information.
Security Exploit
Trojan Horse = A trojan horse is malware program that pretends to be useful or helpful and runs malicious code in the background.
Rootkit = A rootkit gains administrator or root access of a computer through various ways then disguise as necessary files that is hard to detect by antivirus software.
Distributed Denial-of-service Attack (DDoS) = DDoS attempts to bring a site or service down by flooding it with visitors.

Question 16

Cryptography

Answer 16

Symmetric cryptography =
2 identical key to open and send

Asymmetric cryptography =
1 private key - to open
1 public key - to send

Question 17

Waterfall Development

Answer 17

You figure out everything you need to do and document them (requirements).Like a waterfall, there’s no way to go back up unless you start over again. You move on to next phase only when current phase is completed.
Requirement
-Design
--Implementation
---Verication
----Maintenance

Question 18

Agile Development

Answer 18

You figure out some of the things you need to do at the beginning. Then, continuously improve, evolve, collaborate and adapt as the development goes on.

• Scrum = goals that can be completed within timeboxed iterations, called sprints, no longer than one month and most commonly two weeks, then track progress and re-plan in 15-minute time-boxed daily meetings, called daily scrums.
• Extreme programming = intended to improve software quality and responsiveness to changing customer requirements
• Kanban = The kanban methodology relies upon full transparency of work and real-time communication of capacity, therefore the kanban board should be seen as the single source of truth for the team’s work.

Question 19

Simulated Annealing

Answer 19

Probabilistic technique for approximating the global optimum of a given function.
For problems where finding an approximate global optimum is more important than finding a precise local optimum in a fixed amount of time

Question 20

Sorting algorithm

Answer 20

In computer science, a sorting algorithm is an algorithm that puts elements of a list in a certain order.
The input data is often stored in an array, which allows random access, rather than a list, which only allows sequential access;