-
- loverajoel/jstips
Summary 🚧
- loverajoel/jstips
-
- []
00. Insert item insider Array
At the end:
var arr = [1, 2, 3, 4, 5];
var arr2 = [];
arr.push(6);
arr[arr.length] = 7; //fastest
arr2 = arr.concat([8]); //slowest At the beginning:
var arr = [1, 2, 3];
arr.unshift(0); //fastest
[0].concat(arr); In the middle:
var items = [1, 2, 3, 4];
items.splice(items.length / 2, 0, 2.2); - Algorithms and Data Structures
1.1. Big O Notation
Growth rate, worst case, scalability, efficiency 1.2. Sorting algorithms 1.3. Recursion 1.4. Big data 1.5. Data Structures - Artificial Intelligence
2.1. Greedy algorithm
A greedy algorithms picks the best immediate choice and never reconsider
it's choices 2.2. Hill Climbing
HCA attempts to find a better solution be generating a neighboring solutions.
Each neighboring solution is generated based on the best solution so far, with
a single element modified. 2.3. Simulated annealing
Always evaluates best possible solutions so far, if not sure roll back to some
previous point, reevaluate and go further with better solution. The better solution
is, the lower the probability you move to a worse solution. 2.4. Dynamic Programming
Break down a problem into sub-problems and solve it, then store it. Next time the same
problem occurs it takes no time to retrieve it.(Memoization)
Combine previous solutions to sub-problems to solve another problem/sub-problem(optimization) 2.5. P vs NP problem (polynomial vs nondeterministic polynomial) 7 x 17 = p ; p x q = 119.
easy to verify, but hard to solve. Problem largely consist of the factorization problem.
It's easier, takes less time and effort to multiply numbers(verify), rather than factorize(solve). - Concurrency
Is a property of programs and systems that allow tasks to run in overlapping time periods. 4.1. Parallelism
Allows 2 or more tasks to run at the same time, provided that the machine has multiprocessing capability 4.2. Race condition
When two processes/actions overlap/cancel each other and causing unwanted rewrites.
4.3. Mutual Exclusion (Mutex)
Lock a process in order to finish ongoing action/transaction without any later interruptions from other
transactions/actions. 4.4. Semaphore. Binary Semaphore
Lock a process based on its priority 4.5. Semaphore. Counting Semaphore
Queue incoming transaction if process is locked, after unlocking hand over to the next in queue 4.6. Deadlock
An issue in concurrency systems, when two process are blocked for trying to exchange/overwrite data
of each other in the same time. - Cryptography
5.1. Symmetric cryptography
5.2. Asymmetric cryptography
Public-private key cryptography
Definitions, Legends etc.