In Linux, directories have permissions too - You can list their contents if it's *readable* - You can access a file in a directory if the directory is *executable* To change permissions, use chmod - chmod 711 file - chmod u+x file (users can execute the file)
Design patterns in 1 tweet Flyweight: support a large number objects efficiently by sharing constant parts of their state (called intrinsic state) Ex: To represent a text document, a Flyweight object is created per character in the character set.
R was created in 1993 at the University of Auckland in New Zealand by Robert Gentleman and Ross Ihaka R is mostly used for data data analysis. In of January 2020, R ranked the 18th most popular programming language
AWS Storage Services - S3: general - Glacier: archiving & backup - EBS: block storage (disks) - Storage Gateway: connect on-premise with storage in AWS infrastructure
Know what version of Python you're using. There are differences. For instance, when dealing with strings: Python 3: bytes contains sequences of 8-bit values, str -> seqs of Unicode chars Python 2: str contains sequences of 8-bit values, unicode -> seqs Unicode chars
HTTP status codes in 1 tweet 1xx: Still processing 2xx: Alles Gut 3xx: Check somewhere else 4xx: Client's fault 5xx: Server's fault
"A year spent in artificial intelligence is enough to make one believe in God." - Alan J. Perlis
Merge sort is a divide and conquer, stable, comparison-based algorithm invented by John von Neumann in 1945 The idea is to split a list into sublists, sort them (recursion) and then merge the sorted lists. Its time complexity is O(NlogN) and space complexity is O(N)
Design patterns in 1 tweet Decorator: Add responsabilities to objects dynamically Ex: in a war videogame, adding accesories to a basic weapon (can be added after creating it)
"Owning a computer without programming is like having a kitchen and using only the microwave oven." - Charles Petzold
Scala was developed by Martin o darsky in 2003 combining functional and object-oriented programming Many its design decisions are aimed to address criticisms of Java object Hello { def main(args: Array[String]) = { println("Hello, world") } }
3 Random coding tips Pay off technical debt Prioritize tasks Don't overlook the details
Big O quick tip Try to remember this pattern: A problem where the number of elements in the problem space gets halved "at each step", will most likely have O(logN) time complexity
"A computer would deserve to be called intelligent if it could deceive a human into believing that it was human."" - Alan Turing
Namespaces are one honking great idea -- let's do more of those! - The Zen of Python
In 2009 Google created Go, also known as Golang to help fix problems that are common at Google where languages like Java and C++ would fall short. Its syntax is similar to C import "fmt" func main() { fmt.Println("hello world") }
Files and processes are the two basic blocs of the UNIX system. In UNIX, everything is a file. Filename are restricted to 255 characters. A process represents a program (a file) in execution.
Hardware is the part of a system you can kick Software is the one you can only curse at
Don't go blind. Use a profiler. "Premature optimization is the root of all evil" - Donald Knuth
"The question of whether a computer can think is no more interesting than the question of whether a submarine can swim." - Edsger W. Dijkstra