Dev terms Flashcards
Big O Notation
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
Recursion
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".
Big Data
Big data describes data sets so large and complex that is impossible to manage with conventional data processing tools.
Data Structures
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.
Greedy Algorithm
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.
Hill Climbing
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.
Dynamic Programming
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
P vs NP Problem
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.
How do computers work?
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#
Parallelism
Parallelism allows 2 or more tasks to run at the same time,.
Race Condition
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.
Mutual Exclusion (Mutex)
Now, whenever there’s an ongoing transaction, the system will lock the account(s) involved in the transaction.
Semaphore
Binary Semaphore =
2 different states.
Counting Semaphore =
More than 2 states
Deadlock
2 oposite transactions crate a deadlock because each transaction blocks its source account.
Computer Hacking
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.
Cryptography
Symmetric cryptography =
2 identical key to open and send
Asymmetric cryptography =
1 private key - to open
1 public key - to send
Waterfall Development
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
Agile Development
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.
Simulated Annealing
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
Sorting algorithm
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;
