Inside every complex program is a simple program trying to get out

There's no test like production

Big O is not the only factor to consider when you think about algorithm performance. Also:

- Disk usage
- Memory
- Cache
- Network
- Concurrency (and its overhead)
- ...

"If you don't fail at least 90 percent of the time, you're not aiming high enough."
- Alan Kay

In MATLAB, for a nxn array A, what does A(:) do?

It creates a n^2x1 column vector. Column, not row, because MATLAB matrices are column-major

2 Quick Interview tips

- Think out loud while solving the problem. Explain your thought process.
- If your interviewer jumps in to help you, don't freak out. It's normal.

If it's worth doing just once, it is worth automating!

The best code is the one you don't have to write.

If the code and the comments disagree,

they are both probably wrong

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