##a few Advanced algo IV categories #study

By “Advanced” I mean — the average programmer without focused study will likely struggle.

  • problems that require recursion-in-loop — rather common
    • but I have analyzed quite a few. Now at a plateau. No thick->thin
  • grid or matrix problems — more common than I thought. My weakness,
    • but I have invested quite a bit. Fast early ascent is over
  • graph problems — sometimes harder than average. Hard for everyone but I often fare better.
  • DP and greedy problems — occasionally easy, but usually non-intuitive
  • single-str or two-str problems — usually hard
  • num-array problems
  • generator problems — not so common
  • problems that require backtracking — rare

However, some of the hardest problems involve nothing but an int array or a single string.

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highest leverage: localSys^4beatFronts #short-term

Q: For the 2018 landscape, what t-investments promise the highest leverage and impact?

  1. delivery on projects
  2. local sys know-how
  3. portable GTD+zbs irrelevant for IV
  4. pure algo (no real coding) — probably has the highest leverage over the mid-term (like 1-5Y)
  5. QQ
  6. –LG2
  7. obscure QQ topics
  8. ECT+syntax — big room for improvement for timed IDE tests only
  9. Best practices — room for improvement for weekend IDE tests only

coding drill:LASTING value4family-well-being]U.S.10Y

This blog post is poorly structured, but let’s not spend too much cleaning it up. Not worth it. Most of the content is repeated elsewhere.

See also  the benefits of coding drill in 4 benefits of coding practice #beatFront and Coding drill is anti-aging

Background: for many years until late 2017, I have focused on QQ, and neglected coding tests.

  • If you bring your pure algo skill from 4/10 to 6/10, it will remain around that level, or slightly lower. It will help you with your high-end job interviews for 5-10 years.
  • a lot of “algo skill” consist of key ideas behind the top 100 common coding questions. (I tried about 1/3 of them.) I feel it’s crucial to review the high-value problems to refresh 1 or 2 key ideas for each problem.
    • Note the various max-profit problems look similar but Key ideas are vastly different.
  • If you rely on your work projects, you will remain around 3/10 😦 Your projects won’t train you for those coding challenges in terms of algo, BestPractice, ECT…
  • Only a small part of the required syntax can be practiced but a lot more practice still needed 😦
  • You may think the STL syntax will become familiar naturally, but in reality over a year our projects used no std::map no lower_bound() no sort() no getline() so most of the basic syntax were not developed!
  • One builds the ECT skills (including syntax) with focused practice, outside the day job. No shortcut. Programmers without this “mileage” won’t have this skill. Just like driving or any athletic or artistic skills.

I’m reluctant to break down by “skill” but ..

  1. quick-n-dirty syntax used for coding test — Yes we can remember most of it for 10Y, based on my experience with perl, java, php
  2. ECT — easy to lose the speed. I feel some of the ECT improvement does remain.
  3. pure algo ideas — already discussed above

Low “churn” — most coding questions have remained unchanged for 20 years.

I also realized that my c++ ECT/BP proficiency is different from my java ECT/BP proficiency.

 

4 technique gains { coding drill #技巧提升

An essential review can be good once a while, but over-analysis can reduce our motivation for practice:(

See also my google-sheet on codingIV types and skills required —

Note I don’t target a skill like “passing all Leetcode tests” since those tests require very refined algorithm, but most coding tests focus on just a decent algorithm with normal test cases. See my letter sent to friends about “hard problems”

benefit : quick-n-dirty
syntax+idiom
other part of ECT best practices
Can we remember after X years? 3Y #highly specific items unsure 4Y
Did we improve through past IV? y they are wake-up calls
Can we improve it on the job? actually no rarely slightly
important in short codility IV? crucial y n
important in white board pair-coding? secondary FB only, not GOOG n
important in long take-home assignment? n n y

—-#1 benefit: syntax+idioms. See ##examples@syntax learning via mock coding IV 

I also realized my data structure syntax grasp is insufficient with STL etc. In a timed coding tests I had no time searching online. I feel STL syntax is more messy.

—-benefit: ECT speed of completion.

I was able to complete many timed online tests but still rejected. Still, I did better than before.

—-benefit: best practices — designs, code smells

—-benefit: key ideas (sometimes insight) into a classic problem. A real insight is powerful and reusable. This is mostly useful when we hit a “previous problem”. See https://bintanvictor.wordpress.com/2018/06/09/study-top-100-common-coding-challenges-to-learn-key-techniques/

This is the #1 benefit to XR.

I feel I hit something similar to previous problems about 50% of the time.

c++4beatFronts: which1to LetGo if I must pick1

Q: Which one to let go, given I have limited O2/laser/bandwidth and mental capacity?

  1. give up BP — biggest room for improvement but least hope
  2. give up codility style — Just get other friends to help me. See codility: ignore overflow, bigO

How about pure algo?

  • already decent? Can improve.
  • diminishing return? Smaller room for improvement? but I can learn a few key ideas about the G100 questions

##failed cod`IV

Here I only list the failed ones. There are many successful ones in ##some@the significant coding IV experiences

 

QQ BP ECT speed syntax algo where
 ? 😦 NA NA ? home c GS tick-engine
NA 😦 NA NA ? home c Tetris
 ? 😦 NA NA ? home c Macq
😦 😦 NA NA NA home j MS-commodity
? ? NA NA 😦 home j Amazon
😦 ? NA NA NA home j MS itr
😦 ? NA NA NA home j MS FIX
? NA good good 😦 codility c/j Mako
NA NA 😦 ? ? codility j FXoption
NA NA 😦 ? ? codility c Jump #3
NA NA 😦 slow good IDE c Bbg 2017
 NA ? 😦 slow good webex c Citadel array-shrink
none ? 😦 good simple IDE j UBS Suntec
😦 NA NA NA ? paper c Nsdq array 0-N
NA NA NA NA 😦 paper c Nsdq day-trading
😦 NA NA NA 😦 paper c FB regex
😦 NA NA NA 😦 paper c Goog
😦 NA NA NA ? paper j Barc SmartOrderRouter
😦 ? ? NA NA NA paper j UBS YACC
😦 NA NA NA NA paper c Bbg London
😦 ? NA NA NA paper c Imagine Software

See C++(n java)IV tend to beat us]4fronts.

Q: where is my biggest coding IV weakness? crack the algo? complete in pseudo code? or get the damn thing to compile and work?

  1. take-home tests usually beat me in terms of Best Practice
    • possibly give up if I must give up something 😦
  2. speed coding tests usually beat me in terms of ECT speed
  3. white-board tests usually beat me in algoQQ