Mostly Software – Page 96

Dec 22, 2019

Did some leetcode problems to practice.
When doing something with only two elements (like check to see which two items in an array add to a target sum), you might be tempted to check the permutations of the remaining array, with each iteration. This is not the fastest. You can get it down to O(n) time by storing a complement map as you move through the array, then you can compare each to the complements to see if it fits.
Pretty much finished all my specific prep for interviews. Now it’s just going through the generic problem repositories, practicing a few each day:

Hackerrank. Leetcode. Careercup (CtCI). Glassdoor. Youtube.

So far I think I like leetcode the best.
5 directly-interview-relevant docs in gdrive. 1 for general process/approach, and then 4 from book notes:

Structure and Interpretation of Computer Programs, Algorithms and Data Structures, Programming Interviews Exposed, Cracking the Coding Interview.

Reminder of great youtube channel for interview questions: https://www.youtube.com/channel/UCNc-Wa_ZNBAGzFkYbAHw9eg/videos.
Alpha = how much you outperform a generic benchmark, usually the S&P500. If that rises 5% in a year and you rose 15%, your alpha is +10.
Beta = how much more volatile than a generic benchmark. If your stock gained 3% in a day and the S&P500 lost 1%, your beta is -3.
Manacher’s algorithm is O(n) for longest palindromic substring: https://en.wikipedia.org/wiki/Longest_palindromic_substring. Fantastic.
Longest common subsequence = a common problem. Look it up.
When palindromes are mentioned, you can reverse the string and then it becomes a longest common subsequence problem (check indices tho).
An 8yr youtuber who reviews toys made $26m last year.
Helped dad backup/update his iphone 6.
Did the amazon coding interview (90m). Each question basically has 20 unittests, 2 of which are shown and 18 are hidden.

On the practice exam, I got 20/20 and 20/20, and finished in 35m.
On the real exam, I got 19/20 and 2/20, and finished in 90m. The first one was good, but something was up with the second one. It passed both visible testcases and then showed “passed 0 of 18 for the invisible testcases” – not sure what happened, but my program was correct so who knows.
Was also possible to have another computer googling the problems and copying the answers. I did it honestly, so I worry about the bar I’ll be compared to. I much prefer a voice/video call, for both authenticity and the ability to prove comprehension verbally.

Went to sunnyvale, madras and fam.

Dec 21, 2019

Walked 4 miles around Atherton.
Chan Sung Jung knocked out Frankie Edgar (38), and now there isn’t an event for the next 4 weeks until McGregor Cerrone.
All presents wrapped and ready. Dec 21st. World record.
SCORE_DAYS was the nominal th/sun/mon. I had to add saturday for these week 16 games. Deployed the supercontest change. Recompiled reqs.
Did a few hackerrank problems:

Side note: hackerrank has a terrible problemsolving interface. The inputs are given via stdin with line separations lol, and the outputs are compared to stdout. This is probably laziness to accommodate multiple languages, but it’s shrouded and detracting.
The difficulty is also widely variant. I finished some “medium” level questions in (literally) 60 seconds, and some “easy” questions took my 20 minutes to read the problem statement and 40m to answer.
Some complexity notes.

Recursion with 2 recursive calls is exponential in time complexity.
Binary trees require 2 recursive calls to traverse, one to walk the left edge and one for the right.
Fibonacci sequences require two recursive calls as well, but you can memoize each one to reduce it from exponential to linear.

For iteration problems, usually just run a while loop and add items to array, or do something else to keep track as you traverse.

Dec 20, 2019

There are so many python dep managers out there now, like my sx-setuptools. Poetry: https://github.com/python-poetry/poetry.
Awesome js recap: https://2019.stateofjs.com/. Typescript/express/react/redux/graphql still king. Jasmine is no where near the top for testing frameworks (jest is #1).
Ear buds died. Ordered 2 more. I still continue to be impressed. Great quality, people around can’t hear, only $7.
I always forget amortization: pay off periodically.
Permutations > combinations. Combos don’t care about order.
Finished CtCI. Went through some of the problems.
Flew LAX -> SFO.

Dec 19, 2019

The Ducati has been stalling a bit. I had originally thought it was misconfiguration of my nonstock levers (I think CRG) where the clutch couldn’t fully engage, but it happens at speed sometimes too. Did a bit of reading and it’s not uncommon. Can pursue a fix if it gets more frequent.
Charged the BMW.
Haircuttt.
Sick. All sorts of weird temps and delirium.
Dentist. The cut should go away in about a week. Good health, just need to not brush as hard. It’s causing more recession. They can fix with bonding if it starts to get sensitive. Deep cleaning scheduled for beginning of jan.
Read more of CtCI for interview prep.

Dec 18, 2019

Some notes from matthew walker:

Practice doesn’t make perfect, practice + a good night of sleep makes perfect.
While asleep, we can’t eat, we can’t run, we can’t take care of our young, we can be hunted, etc. If sleep didn’t serve an absolutely VITAL purpose, evolution would have made the biggest mistake of all time.
We sleep better in slightly colder temperatures. When our hands/feet are warm, vasodilation occurs. Blood flows outward to the skin more, reducing core body temperature. This is why you get better sleep with socks. The same vasodilation occurs after a bath.
We don’t have a “credit” system for sleep like we do for fat (eat more before winter, use fat stores) because we are the first species in the history of time that has ever faced lack of sleep. No animal has ever had to evolve to handle this, and it’s self-inflicted.
20hrs awake = same impairment as 0.08% bac.

More record highs for stock market yesterday. My ZYME surpassed 45. DJ 28367 s&p 3193 nasdaq 8823 10yr treasury 1.878. Bitcoin is down to 6613.
Finished programming interviews exposed. Tons of notes, practice problems, brainteasers, coding tests, and behavioral examples.
Started cracking the coding interview.
Pro bowl selections: http://www.nfl.com/news/story/0ap3000001089218/article/nfl-reveals-rosters-for-2020-pro-bowl-in-orlando.
First day without the cat!
COMPOSER DAY.

John Williams: star wars, indiana jones, harry potter, home alone
Klaus Badelt: pirates, time machine
Danny Elfman: nightmare before christmas, lots of superhero movies
John Powell: dreamworks
James Horner: titanic
Hanz Zimmer: everything
Howard Shore: lord of the rings

Multi-year university hospital study has good things to say for keto: https://medium.com/@JPMcCarter/the-top-12-keto-myths-debunked-after-150-000-days-of-patient-care-9502383d4e8c.
At ~8:35am ZYME was up 6.06% giving me a day return of $666.86 thus far. Devilish.
Scheduled dentist appointment for tomorrow.
Still sick but run gym push.

Runner’s “neck check” – if your symptoms are below your neck, you’re probably better off resting than exercising.

Being cold doesn’t give you a cold, but airborne bugs spread more easily because the medium is denser.
Remember of the terrible complexities: n^2 (quadratic) then 2^n (exponential) then n! (factorial) is the worst.
Remember stack is static. It’s the variables, function calls, scope, etc. It’s very fast. The heap is for dynamic allocation. It’s a little slower. Both are in RAM. Threads share heap, but each have their own stack.
Big endian = most significant bit stored first. Little endian = LSB first.
TSLA about to hit 400, doubling in 6 months. I remember it being in the 170s in June.
Committed week 16 lines, backed up prod db, submitted picks.
Updated the widgetbot shard back to the main one, disweb.dashflo.net. They seem to have fixed their dos problem, so greatplainsmodding was no longer needed (and was offline). Verified on desktop and mobile in dev.

Dec 17, 2019

In december, mutual funds drop in market value by ~5-10% because they’re distributing capital gains for tax purposes. That drop in equity is coming to you in cash. Think of it like a dividend.
Cleaned and vacated most of the house. Started packing. Everything is so organized now.
The bluetooth headset arrived and I set it up. Works well. Did some tests. My voice is not as clear as regular speakerphone, but typing is much quieter.
737 Max halting production, Boeing dropped 4%.
10 years old, but a good AMA from an individual algotrader: https://old.reddit.com/r/IAmA/comments/9s9d7/iama_100_automated_independent_retail_trader_i/.
Finished all christmas shopping. $300.
Netflix confirmed the tech interview with the CI manager, which totals 5 phones now.
Ordered more post oak and maple chunks.
Installed new kitchen and bathroom bulbs.
Butterflied and oven-roasted a chicken. Fresh garlic, butter, and some of my red rub. Added to fried rice with egg.
Interesting JRE with a sleep scientist from berkeley: https://www.youtube.com/watch?v=pwaWilO_Pig.

Dec 16, 2019

New major version of coverage. sqlite storage, json report, contexts, relative filenames, dropped support for py 2.6/3.3/3.4.
Compiled new sbsc requirements and updated the banner.
Ordered a headset for the coding phone interviews where I need my hands to write.
Remember js spread operator or rest parameter: …obj
Played with coderpad to familiarize myself. Can write in many languages, set key bindings to vim, etc.
Webcammed practice interview, both tech and worklife questions. ~20m/350MB@720.
Placed grocery order with amazon (whole foods). Arrived a couple hours later.
Citadel tech test was moved to first week of Jan when the proctor is back from holiday.
Disney reached out for a senior software engineering position.

Scheduled a phone call for later in the day.
Spoke for 20min, discussing the opportunity.

React/node/docker/mongo/k8s/aws/lambda.
Exciting projects. Thrown right in. Move teams quite a bit.
Almost all enter as contractors before full time. 50% insurance, no 401k. Paid hourly, but usually ~175k. No equity.
Shorter hours.
They’re an entertainment company before a tech company.
Just one 30m coding call, then onsites.

Review of old notes. Consume again and again, commit to memory.

Bazel, c++, java. Lighter on python rules. Build and workspace files. Still similar to my old sx-setuptools, just files that take inputs and produce outputs. What files to build, what to do with it, etc.
Computers perform tasks. Humans should be solving problems.
Trees are just linked lists with multiple pointers, really. Graphs are just trees with no root.
DP is generically named. Just solve subproblems and cache/memoize.
C++ headers contain the declarations, source files use them.
Polymorphism. Two children inheriting the parent but using a method/attribute differently (e.g. parent animal with noise() method, child cat would noise(‘meow’) and dog would noise(‘bark’)).
let = block scoped. var = function scoped.
Lists and dicts are basically the only mutables in python. All the primitives are immutable.
Groovy is part of the java ecosystem.
Python > byte code (pyc) > machine code.
Netstat and wireshark.
Can think of websockets as just persistent http connections with a server over tcp/ip, where a socket is any general tcp/ip connection.
Every thread has its own stack (and registers), but all threads in the process share a heap.

A$ap and chance most of today.
Fed mouse.
Went through Amazon’s leadership principles and wrote examples of each: https://www.amazon.jobs/en/principles. Having gone through all, examples came readily. The principles were generic.
Received the online test for amazon. It takes 2 hours, and I can complete at any time in the next 2 weeks.

The coding portion is 90m, 2 explicit “write a function that returns this” questions.
I did a full demo test, finishing both after ~35min.
They use Aspiring Minds (not codepen or google docs). No proctor.
Asked Renee if it scores higher by submitting earlier, or if all extra time should be used improving/cleaning/commenting.

Amazon has such a crazy list of products: https://aws.amazon.com/products/.

Did some research and took some notes in gdrive. Main ones:

EC2/Lambda for cloud servers and compute.
Aurora/DocumentDB/ElastiCache/DynamoDB for all types of databases.
Beanstalk/Amplify for building web/mobile apps.
S3 for storage.

Bought new bathroom and kitchen light bulbs.
Run gym pull.
Washed all mesh running shoes with soap.
Scheduled haircut for thurs.
Started reading ctci.