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Initial commit — imported from GitHub
2026-08-25 19:14:07 -06:00
---
layout: page
title: Practice Log
---
### Sept 22
### Sept 16
Tmr try to grok:
- [combo sum backtracking](https://www.youtube.com/watch?v=MTI2wc8s0BY)
- [permuation backtracking](https://www.youtube.com/watch?v=KukNnoN-SoY)
then draw recursion tree for generate parenthesis
### Sept 6
New goal to keep up.
- solve questions you've seen before in less time
- resolve harder questions days or a week after you've learned them
- round robin thru all types of problems
- can solve questions from daily problems, explore cards, lists, difficulty, categories, etc
### Sept 4
The last few days I've just stressing out over the Facebook phone screen. It turns out that the actual interview had pretty easy questions (even though I didn't answer all the questions). But as the days approached, I just kept thinking that I am not ready. I saw people say on Leetcode that they're phone screens are leetcode difficulty questions that I was not ready for.
To relieve the stress, I would need to keep up my Leetcodig skills. I also need a fun project to releave myself from telus boredom and as a break from leetcoding. I think
### Sept 1
Procrastinating from solving problems with my facebook interview coming up soon. I found myself procrastinating by doing telus work. Next time, I might need to have "my own project" to keep me busy. Maybe a stock tracker or a real estate property finder.
___________
Somethings to make studying easier:
- listen to something relaxing or podcast
- forest app
- keep spreadsheet of questions solved
- start by listening to something CS related (CS50 - Harvard Intro to AI)
___________-
### Aug 31
After taking the weekend off from studying, it's now Monday and I need to get back to the mindset of solving problems for my Facebook phone screen on Thursday. To relief the stress, I've opened Spotify to some relaxing music and I'm going thru my "Review List".
### Aug 27
Got the question [Find Right Interval]() today for the daily challenge and it seems doable. However, I messed up the initial implementation and had to spend a bit of time debugging. This debugging time should be factored into solving the problem so now I should work on speed of implementation and debugging.
So leetcode time should be split between:
- doing new medium or hard problems (from daily challenge or from lists) (work on learning new techniques)
- interview.io or pramp (video conference practice)
- on meh days
- solve easy questions for motivation
- reviewing old problems in a round robin fashion (work on speed and recall)
I may need to have another system for tracking leetcode problems. I'm outgrowing jekyll, probably need to keep track of revisits and timing. Outsource solutions database to a blog or something (substack?).
__________
On the motivational and sustainable end, leetcoding could be very dry (it's a grind afterall), so intermix it with rental reseach and life planning. Like what you would do in a regular work day anyways.
__________
On real estate investing, [this video on bigger pockets](https://www.youtube.com/watch?v=u83O2l1QEj4) has first steps on what you need to do to start your rental business career. It boils down to get good at the math.
You can start by doing the math on your current property.
### Aug 25
[programmer coach](https://www.programmercoach.com/)https://www.programmercoach.com/
___________
SQL Practice, take the "practice sql questions.doc" from facebook and try them in sql fiddle.
### Aug 24
Sometimes on your meh days, you just have to warm up with easy questions.
[interview experience post](https://leetcode.com/discuss/interview-experience/808191/google-l3-mountain-view-august-2020-offer)
On your days when you're very productive and solving random problems, take some time to look over life stuff like real estate and future planning.
### Aug 23
try [this](https://leetcode.com/problems/heaters/) problem. it should be easy
just do a bunch of easy problems to see if you can get brute force solution on your meh days
round robin thru each type of problems in last 2 weeks before interview:
- 1-2 sql questions
- 1-2 string/array problems
- 1-2 matrix q
- 1-2 island
- 1-2 binary search
- 1-2 trees
- 1-2 bfs
- etc
### Aug 20
Getting very burnt out but my facebook interview phone screen is coming up in 2 weeks.
I'm just going to have to find the build a curriculum and follow thru. Leetcoding is something that I'm not going to enjoy and never will but I will have to do it to continue living a better life. Much like going on a run or exercising.
Things are getting busier at work. Not caring and doing the minimum has been working and it helps my sanity.
As for leetcode and studying for interviews when your interview is coming up.
=> admit that you wont be able to remember all your problems so just make it a plan to study all the ones that you have reviewed
=> focus on quantity than quality
___________-
Today, I'm feeling kinda meh but I've gotten in the zone by doing random questions and SQL problems. Sometimes it's nice to just do random problems and figure it out as you go along without any pressure. Focus on quantity>quality on these meh days. Aim to increase submission count in leetcode profile. Keep doing it until you get tired. You got the time, now you just need to keep up the motivation. The interview is partly luck based so you're just increasing your chances.
Another thing on can do on my "meh days" is just to randomly pick medium problems and practice them.
Can also do hackerrank practice on my meh days.
### Aug 18
Got [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) problem on pramp. I saw it before, got the algorithm with help but couldn't write code for it.
[company specific questions list](https://github.com/MysteryVaibhav/leetcode_company_wise_questions)
Do this pattern:
```
LeetCode Studying Approach
1. Do Breadth-First Scan of “Easy” questions from each Topic on Leetcode
1. Try to get it right on the first try
2. Should be finishing these in < 10 minutes
3. Take note of which sections you struggled at (the following was for me)
1. Trees
2. Dynamic Programming
2. Do more “Easy” questions from the topics you struggled at
3. Shuffle “Medium” problems
1. Only do the problems you are not 100% sure how to do
2. Start a 25 minute pomodoro timer and attempt to solve it
3. If the problem isn’t solved in 25 minutes, take a look at the discussion section but do NOT look at code just yet
1. Reset the timer and do another pomodoro
2. Once the problem is done, look at the discussion section and understand how other people solved it
3. Write this problem down in your notes as a problem you need to revisit
4. Do the popular “Hard” problems from each Topic
1. Try to finish these within 45 minutes
5. Do a mock interview AT LEAST once a week
6. Towards the last month of interview prep, do the 1-month term plan in EPI on PAPER
```
### Aug 17
Topics from groking
--------------------
Pattern: Sliding Window
Pattern: Two Pointers
Pattern: Fast & Slow pointers
Pattern: Merge Intervals
Pattern: Cyclic Sort
Pattern: In-place Reversal of a LinkedList
Pattern: Tree Breadth First Search
Pattern: Tree Depth First Search
Pattern: Two Heaps
Pattern: Subsets
Pattern: Modified Binary Search
Pattern: Bitwise XOR
Pattern: Top 'K' Elements
Pattern: K-way merge
Pattern : 0/1 Knapsack (Dynamic Programming)
Pattern: Topological Sort (Graph)
### Aug 14
[back2backswe course](https://backtobackswe.com/pricing?utm_source=facebook&utm_medium=cpm&utm_campaign=23844860978500459&utm_content=23844860982700459&fbclid=IwAR3YvZ76JBQ2Mg_By8XxRbNMPH-wfkFOSMFs3dVSQTCi9Rpj7jgKVou3eTY)
Worked on:
- top k frequent elements
- k most frequent elements
- move zeros
- reverse vowels of a string
### Aug 13
[my youtube channel](https://www.youtube.com/channel/UC_2uIVR51P4EuccbJOJvcQA/videos)
[youtube studio dashboard](https://studio.youtube.com/channel)
### Aug 11
Interviews
- Amazon - Missy is contact, need to complete coding assessment
- Facebook - Shone is contact, need to complete 1 hr phone screen with data engineer
1 hr on coder pad
25 min questions on sql, 5 max
25 min questions on coding, 5 max
5 min for Q's
the bar is 3-4 questions on each one, it gets progressively harder
best way is to hit up leetcode and hackerrank and practice those on medium
if you can do 3-4 of them in 25 min, you're ready
__________-
sql resources
- [coderpad.io sandbox](https://coderpad.io/launch-sandbox)
- [summary of sql qustions on leetcode](https://byrony.github.io/summary-of-sql-questions-on-leetcode.html)
- [What I realized after solving 100 leetcode SQL questions…](https://towardsdatascience.com/sql-questions-summary-df90bfe4c9c)
- [hackerrank](https://www.hackerrank.com/domains/sql)
- [advanced sql q&a](https://www.programmerinterview.com/database-sql/advanced-sql-interview-questions-and-answers/)
- [sql zoo](https://sqlzoo.net/)
__________
[facebook recruiting link](https://www.facebookrecruiting.com/portal/home)
[fb data engineer prep](https://www.facebook.com/careers/DE-prep-initial)
- material in /home/steve/tmp/facebook_interview_prep
### Aug 9
Educative.io is good for knowing which problems to work on and sometimes have decent explanatinos.
Just use educative.io as a list to get thru and feel free to use the explaination in conjunction with youtube to understand the problem.
### Aug 8
I just learned that there's another more intuitive way to do the subset/permutation problem without backtracking
[subset - duplicate and add next item](https://www.educative.io/courses/grokking-the-coding-interview/gx2OqlvEnWG)
It's much more about how you articulate the problem than knowing the problem. Recording yourself should help with this.
______________
Strategy for interview prep:
- review leetcode questions on jekyll
- hackerrank interview prep
- educative.io - groking coding patterns
System
- educative.io - groking system design
Behavior
- educative.io - groking behavior
You can even use educative.io to teach for passive income:
https://www.educative.io/authors
### Aug 7
educative.io
----------------
just search for all "groking"
[groking coding interview patterns](https://www.educative.io/courses/grokking-the-coding-interview)
[groking dynamic programming](https://www.educative.io/courses/grokking-dynamic-programming-patterns-for-coding-interviews)
[grok behavior interview](https://www.educative.io/courses/grokking-the-behavioral-interview)
get 1 month subscription and download using [scraper](https://anotherdev.xyz/educative-io-course-downloader/)
- [downloader](https://github.com/shihabmridha/educative.io-downloader)
[top educative courses](https://medium.com/double-pointer/top-courses-on-educative-io-aa8179682a2d)
try hackerrank as well
- interview prep kit
- tries
- topological sort -> educative.io has one too
nick white has 300 problems solved as of dec 2019
### Jul 30
I've been falling off the behind on my practice. In the last few days, I've solved many problems and practiced many types of problems inlcuding:
- various types of binary searches problems
- dfs technique in level order problems
- heap based problems (kth most frequent elements)
I think taking a step back from doing new problems and reviewing older problems that you've attempted is good once in a while. There are a couple of study habits that I've found effective while studying algos:
- need to dedicate at least a few hours per day every day
- don't spend too long on a problem if you can't figure it out
- space repetition, review all types of problems occasionally
This falls within the "Principles of Life" that I've been building up slowly throughout the past couple years:
- Do not worry about your stock portfolio, just buy and hold
- Do not waste time on Telus work, just use that time on getting better at leetcode. But do not stress out over not working for Big4.
- Use other time to get better at cooking/chinese/fitness/photography/business/etc?
### Jul 28
[Julia Zines](https://wizardzines.com/)
[Leetcode Behaviroal Interview](https://leetcode.com/explore/interview/)
### Jul 24
[Amazon Behaviroual Interview](https://www.1point3acres.com/bbs/thread-307462-1-1.html)
[space repetition advice](https://leetcode.com/discuss/interview-experience/426561/amazon-sde2-jul-2019-reject-lesson-learned-to-never-fail-again)
### Jul 23
I was able to solve Max Depth of Nary Tree by myself today on my first try. I remembered the solution from max depth of binary tree and just modified it from 2 left and right children to iterate thru all children.
Understanding the concept and being able to modify the code is what I needed to do.
Kevin Naughton Jr.
[Getting Laid Off](https://www.youtube.com/watch?v=tAQ-s90eaKQ)
[Dealing With Failure](https://www.youtube.com/watch?v=sWfTIQ2wX_0)
### Jul 22
I did a few linked list problems but even though I was able to do those at an earlier point in time, I still write buggy code. Been trying to do a few more. Learned a few techniques like dummy nodes and prev pointers.
### Jul 21
[Anxiety During Interviews](https://leetcode.com/discuss/interview-question/746391/my-faang-interview-experience)
### Jul 20
Wasn't able to solve the Remove Linked List Elements problem, even though it was an easy problem.
I should start solving a bunch of linked list problems one after the other. Kinda like how I gotten "comfortable" with tree problems.
Also, should start publishing to leetcodegym.substack.com
Btw, it seems like I am the owner of both substacks:
https://bootstrapersjourney.substack.com/publish/settings
https://leetcodegym.substack.com/publish/settings
### Jul 19
Okay, it's been a couple days where I've taken a break from the daily challenge and gone to "think of a business idea" but now I'm back. Both are painful to do but are necessary. I can use one to motivate myself to do the other when I get sick of one of them.
The leetcoding one should be my 40hr per week job where 20% is used to do my side hustle (business).
### Jul 17
Aside from playing around with Anki, I've started just reviewing some of the problems that I've done in the past and it's a nice refreshing feeling. It lets me know that I'm actually improving.
### Jul 15
Thinking about moving some Leetcode Gym jekyll articles over to Anki for studying.
### Jul 11
[Recursive backtracking](https://medium.com/leetcode-patterns/leetcode-pattern-3-backtracking-5d9e5a03dc26)
### Jul 8
[Leetcode Patterns](https://medium.com/leetcode-patterns)
[Backtracking Standford](https://see.stanford.edu/materials/icspacs106b/H19-RecBacktrackExamples.pdf)
### Jul 4
Coded July Leetcode Challange (Ugly Num 2), got it working but TLE for large N.
Then did longest padlindromic substring, can get it working for odd palindrome but not even.
Sometimes, you just have to work on your coding ability and translating ideas to code. Even if solution doens't work out.
Focus on getting more practice in. Especially coding pratice.
### Jul 3
Another day, another battle to decide whether to continue working on leetcoding or work on business/self improvement.
Today, I attempted the July Challenge "Prison Cells after N days", I got most of it and was able to code up solutions for small cases of N, but was not able to get the optimized solution for N=1 billion.
Eventually, I ran to my 2hr limit and just wrapped it up.
One area where I have gotten better is reading solutions and understanding the idea behind the code. Just need to increase speed now.
[Python Visualizer](http://pythontutor.com/visualize.html#mode=display)
___________
Morning - Solve Daily Challenge
Afternoon - Work on Business Project?
Evening - Review old Leetcode problems
___________
When it's time for an upcoming interview:
- review "Review Problems"
- create a "algorithm cheat sheet"
___________
Focus on communicating / explaining a problem:
- Answer on Leetcode discussion board
- Post a blog post
- Etc
### Jul 2
I've learned enough to self-correct. Time for retrospective.
Things you could start doing differently to improve your studying:
- build a personal curriculum (graphs, backtracking, binary search, etc)
- mark similar questions together
- revisit old problems regularly (whether solved or unsolved)
- unsolved problems should be visited sooner
- upvote problems that you want to focus on
- interactive way to mix running code with flashcards?
- multiple choice: fill in this "block of code"
- take pictures of notes and upload them with whiteboard filter
- turn some problems that you've worked on into blog articles
- have some sort of version control so you can see your solutions evolve
- differentiate different types of solutions for the same problem (ie: recursive vs iteration vs xor)
- time your exercises
- allow input for space and time complexity
- how fast can you review all your solutions if you had an interview in a week?
- round robin thru each type of category
- have 2 types of study session: broad or by category
- show some type of visible progress
- make it easy to create leetcode flashcards
- make it easy to convert some of these articles into blog articles
- have flashcards link to jekyll blog
Instead of making an app, create a study schedule:
- week 1:
Make Review Cheat Sheet:
- Dynamic Programming
- Backtracking (Permutations, Subsets)
- Flood Fill
- Reverse Linked List
- Merge Intervals
- Binary Search
Easy
- BFS / DFS
- Trees
- LCA
- Hashtables (Two Sum, Isomorphic Strings)
1)
### Jun 30
I realized I can't even work with Steve and Mayuresh on a project where there is no communication or leadership/accountability. Fuck those guys too.
They are finally asking question in the 11th hour and I have lost all my willpower to care. Just going to keep leetcoding and deflecting their questions.
### Jun 29
Did the June Daily Challenge all by myself on a brand new problem. It was the Unique Paths Problem and I solved it using the bottom up dynamics programming approach. Practicing all those similar dp problems have really paid off.
____________
Rant:
Johnson, Gus and Yvonne asked for an update on SMS Whitelisting and CPG. Eventhough nothing was done, just lie to their fucking faces about it being wrapped up. Tell them what they want to hear and get them off my back.
_________
I've built the habit of leetcoding in my free time. This has become the norm and it requires less will power to keep up. Just like running daily now, whenever it's a "normal" day, I am growing.
### Jun 28
I did the REconstructIternary problem almost all by myself. At least the first example works.
Mark down questions that you could do and ones that you have no idea how to start.
- count and say
- reconstruct iternary
__________
Today, upon working on the Perfect Square problem, I went back to visit the Coin Change problem (change making problem) because Timonthy H Chang said it was similar. After watching Back2BackSWE video, I finally understand how the problem is solved. Sometimes, you just need to come back to a problem after gaining more insight.
### Jun 27
Working on the Perfect Squares problem and I'm starting to identify subproblems by myself.
Also, in the last couple days, I've been working on backtracking problems. Should work on "similar types of questions" at the same time so I can identify patterns. Maybe make a study curriculum.
_________
Time to add a new habit?
- chinese / cooking
- writing / blogging / tweeting and building audience
Start building these small habits slowly. And be realistic.
Got the leetcoding habit down.
Should expand and do blogging habit next.
### Jun 25
Today, I just spent 2 hours trying to get DS to run my CommandLineRunner after Andrei's changes. FUCK!!!!!
After that, I just into issues because teh Auth.net prod credentials were incorrect. Stupid problems. In comparison, leetcoding is easy shit.
### Jun 24
I just watched David V's course on "Everybody can build a Twitter Audience" and it convinced me that I need to gain credibility before I can start any entrepreneurial adventure. Since I'm already working on leetcoding, I can start small and tweet/post my leetcode solutions on medium/leetcode/twitter, etc.
It's better to look at solution, learn it and move on than to get stuck and waste hours on a single problem. You can always return to it later or turn it into a blog article to cement your learning.
The key thing is that you want to gain credibility and have something to promote later on.
### Jun 23
Need to do telus work first. Then go back to Complete Binary Tree Node problem.
I think I've successfully built the habit of leetcoding a little bit every day.
### Jun 22
Make a timeline for reaching milestones. (IE: by August, start applying to tier B companies)
Do June Challenge, then work on permutation problems. Do not spend more than 30 min figuring out a solution and not more than an hour coding it.
Another list of questions: https://docs.google.com/document/d/1wUCqhVHydWiDk6FJdFLSMpgigNrGcs4OFZg0Wa7JGEw/preview?pru=AAABcwEKa6A*jTAyJNFMW1ButNqUo_V6zA
When a problem is really hard to understand, try debugging, putting print statements or finding a solution to a similar problem.
### Jun 21
I have definately stopped consistently doing the June challenge. I should get back into the habit of doing it. It's about how you recover after getting off the wagon.
### Jun 20
I tried the weekly contest. The time pressure is there. There are also virtual contests where rank will not be affected.
When the contest is finished, you see your rank amongst other ppl. For my first one, I got 1/4 question correct with a rank of 9316/13807.
### Jun 19
Other than doing problems from a problems list, can also go thru youtube video playlists of known leetcode youtubers.
Add due dates to learn certain tasks:
- 1 night to learn dijkstra and bfs
- 1 week to learn dp
Been learning some advanced algos recently:
- Dijkstra
- Rabin Carp
- KMP substring matching
Practice whiteboard/paper space management
Do this graph problem, it has every graph algorithm below:
https://leetcode.com/problems/network-delay-time/discuss/471164/Python-DFS-BFS-Dijkstra-Bellman-Ford-Floyd-Warshall
### Jun 18
Time to do some retrospective:
-----
Doing daily problems have been slowing down the past week. Need to keep monitor burnout/stress level.
Now that I've worked on over a hundred problems on leetcode. It's time to go back and review some of the ones that I didn't get (or do some faster and more concisely)
Things that have worked:
- this journal
- this jekyll blog for easy tracking of problems
- this site doesn't actually make me review questions, but it does have my old solutions and some notes so I can reference them in similar problems
- try to gather a bunch of similar type problems and do them in batches
----
Get to the point where the skill of doing coding interviews is a science. Create your own list of "must review" problems before an interview. Have those problems be ones that you have worked on before because you will never be able to do all the leetcode problems ever.
---
### Jun 17
Today, do cheapest flight problem (dijkstra) and leetcode daily problem (union find).
Get used to tryign out solutions and being wrong in leetcode. It's better than being wrong in the actual interview.
----------------
Try rewriting Num Islands solution more concisely from techniques learned from Surrounded Region (for x,y in neib_list) and itertools.product()
Maybe instead of going thru new problems, go thru the ones that you have done before and make sure you can write them concisely and can communicate them well.
--------------
Leetcode post for writing concise Python code:
- https://leetcode.com/discuss/general-discussion/459791/Special-data-structures-in-Python
- https://yangshun.github.io/tech-interview-handbook/landscape
Another list of leetcode questions:
- https://yangshun.github.io/tech-interview-handbook/best-practice-questions
### Jun 16
Spent the morning working on telus shit. what a waste of time.
Today, I went thru the BFS and Dijkstra chapters in Grokking Algorithms book. It does a very good job at explaining for visual learners. Tmr will attempt some dijkstra problems.
### Jun 15
Today, I spent most of the day with the Cheapest Flight problem. I didn't quite get it even after looking at the code so tomorrow, I will focus on understand Dijkstra at a deep level before going back to the problem.
Check groking algorithms ebook for dijkstra chapter.
Can also read "competitive programming" ebook.
-----------------
I read somewhere that Leetcoding is like going to the gym for your coding skills. It's a slow marathon. That falls in line with my experience that you can't cram for an interview. I will just have to incorporate it into my daily routine or work routine.
Since you value your time, your 9-5 is when you should be leetcoding. Treat it like a job and don't bother leetcoding outside office hours.
### Jun 12
Start using interview.io sandbox to practice, they have Python autocomplete and executes code on save. (Much nicer than VS Code).
### Jun 11
Just finished the practice interview. I got this question in the interview:
https://leetcode.com/discuss/interview-question/368038/Amazon-or-Onsite-or-Group-Isomorphic-Strings
It went okay. I surprised myself when I actually came up with a solution myself in the allotted time, even though it wasn't optimal. For your practice, allocate some time to problems where you just figure it out yourself and don't stop unless you've tried for over an hour. Probably best done in some of the easier types of questions (ie: arrays, strings, hashmap).
Some other feedback has been left here:
https://start.interviewing.io/feedback/J2aykIDapnWN
Key points were:
- ask clarifying questions
- always review space and time complexity (i got space complexity wrong)
In every interview, you will always feel unprepared and you will even stress out DURING the interview. You will want to give up. Need to find some way to handle the stress and keep tackling the problem.
--------------------
Have a practice interview today at 3pm. Should start practicing using the online environment:
https://start.interviewing.io/interview/playground?tutorial=true
It also helps you with your walk-thru dry debugging. When you're doing a dry walk-thru online, type out the array in its current state along with all tracker variables. For example:
```
# 2 0 2 1 1 0 i=0 s=0 e=5
# 0 0 2 1 1 2 i=1 s=0 e=4
```
When you run the code, you can print(num, trackerVars...) at the end of the loop and verify what you get when you execute matches what you think you should get.
Getting prep'ed for my practice interview. Just reviewing all the different "bag of tricks" by going thru jekyll blog.
I should make my own list of problems to "review before an interview". Should be a handful of problems that I can review in a short amount of time.
After your interview, you should go and find it in the showcase and see where you can improve. So give it all you got.
### Jun 10
Search Insert Position
----------------------
I did the problem "Search INsert Position" all by myself. It was an easy binary search question, but it's usually one of the ones that I always failed at.
I started with what I know about binary search and modified it by thinking of all the edge cases and eventually wound up at an acceptable solution.
Looking back at some of the LC discussions, I may have over-complicated it and wrote more than I need to. The classical binary search would have suffice with a single line modification (return left if none found).
I posted my solution in the discussions for feedback.
Validate Sudoku
----------------------
Also did validate sudoku problem. I did it within a reasonable amount of time. The debugger helped with finding bugs such as ignoring ".".
It wasn't a logic problem. Just a trivial mistake.
Rotate Image
-----------------------
Transpose and Flip. This is the second time that I'm seeing this and I really worked hard to understand it the first time.
The second time, I was able to:
- recall "the solution"
- code up the solution and get the array indexes and loop ranges correct (things I usually mess up on)
It turns out these problems are actually easier if you solve them a few times before. So it really is all just about practice and not purely talent.
------------------
Did the Hackerrank Data Engineer BS assessment yesterday. It was pretty BS. It's a good reminder that these algo questions are the easiest way to go if you get good at them.
P.S. need to categorize binary search as its own categories and practice a bunch of those questions, just like strings
### Jun 7
Booked a peer interview for Thursday @ 3pm. Should start watching other interviews from the showcase.
https://start.interviewing.io/showcase
-----------------
Teck mining company, who has no business giving technical interviews, are also giving out hacker ranks assessments now.
This whole industry has gone to shit.
### Jun 6
Goal: finish easy collection by wednesday.
Get to the point where you can read solution and understand/code it. If you don't get a solution, keep using other resources until you can understand it. You will eventually reach a eureka moment.
At least be able to comment on the code. Just find the systematic approach to get the best bang for your buck for each hour of studying.
Don't compare your ability with anyone else, just compare to your past self.
### Jun 5
Did the problem "Plus One" all by myself without reference. Sure, I took a bit longer with some corner cases but it's definately a confidence booster.
-------------
Use the Python debugger in VS Code. F5 to debug, F10 to step over.
------------
Going thru some of the SQL problems in preparation for the SQL online assessment. I'm realizin it's not just about knowing algorithms. Getting good at interviews is just about getting good at the skill of being tested. It's not about being a good engineer and completing projects, it's about being good at leetcode problems and hackerrank shit.
https://www.hackerrank.com/dashboard
------------
Spent longer than I should have on Longest Common Prefix. It should've been an easy String problem but I'm not familiar with the basic String functions (ie: index() vs find()).
I need to spend more time on String problems too. Thinking they're too easy and avoiding them is a mistake.
-------------
Leetcoding is now full-time job. Business ideas/Real Estate are side hustles. No time for real work.
If you can't understand a problem. Try to understand as much of it and revisit it the next day. Mark it down as "Attempted" in the Solved Problems page.
After a while, you should go back and "revisit" all the ones you marked as Attempted.
Don't get stuck on any one problem. Your goal is to move ahead and do as many problems as possible with deliberate practice.
### Jun 4
I'm starting to realize there's no way I'm going to memorize the solution to all these problems. But I'm starting to feel like it's actually possible to "recite" these solutions in an interview if I do enough of them. It's just going to take a lot of time and practice.
So I would still have to spend all my available time on it for a chance to get lucky in an interview. Still, it's something that I should do if I have a pointless job. But I should still work on other stuff in life if I can make the time for it.
### Jun 3
I studied one new type of problem (two city scheduling). It's a greedy problem that I probably wouldn't have encountered but I did it because it was the June challenge.
That also brought me to redo (Merge Intervals) because of the foreign Python syntax to sort by first element. I need to practice python fundamentals instead of doing my Java style habits.
Python practices here:
- https://www.hackerrank.com/domains/python
- https://learnxinyminutes.com/docs/python/
### Jun 2
Today I've done 6 problems. 5 were easy and 1 (reversing integer), I had to analyze how they handled overflow.
Something that I'm realizing is that even if I have a bunch of easy questions, it still takes a long time to do a bunch of them. And the "harder" questions could be solved in the same amount of time if you've memorized them.
Your willpower to keep doing another easy question will also be drained. At most, you might be able to get through 5-6 easy problems per day.
So the only way to do good on interviews is to do a bunch of problems, memorize them and find ways to practice more problems right before your interview.
Also, read this:
https://leetcode.com/explore/interview/card/coding-interview-strategy
-----------
Also found this other youtube channel for coding interviews:
https://www.youtube.com/channel/UCpLC2ohmappF2iUsWYRnsxg
So we have "Terrible Whiteboard", nick white and backtobackswe.
### Jun 1
Doing the list Leetcode Top Interview Questions Easy List:
https://leetcode.com/explore/interview/card/top-interview-questions-easy/
Just want to see if I can do all the easy ones now that I had 3 months to practice.
### May 30
Made a python script that generates "Solved Problems" listed by last modified date. Hopefully this will help with space repetition.
### May 29
Studied
- Set Matrix Zeros
I attempted Set Matrix Zeros but ran into gotcha. When you modify the matrix in place, it will screw over teh zeroing logic. This is like a gotcha that I found when validating BST. It seems pretty simple but there's a gotcha. The only way is to just do this algorithms and remember the gotchas.
I swear these problems really make you feel stupid and the only way to overcome them is to play the stupid game and memorize the problems and solutions.
### May 28
Reviewed:
- num islands
Found [this](https://leetcode.com/discuss/general-discussion/655708/graph-problems-for-beginners-practice-problems-and-sample-solutions) great list of graph problems.
Use the forest app to focus and not get distracted. Remember, leetcode first priority, shopify is a side hustle.
### May 27
Review:
- search matrix
Studied:
- Water with most water
- house robber 2
Today, I did a brand new problem "Water with Most water". I jumped straight to the solution, read the optimum approach and was able to code up the solution myself within 25 min.
- The more I'm working on leetcoding/app dev/spending time with loved ones, the more i'm realizing that time management is key.
- Think of leetcoding as full time job and dropshipping/app development as side hustle
- I think last time I wasted time on Project Euler and UVA Online Judge but they were not tailered towards interviewing enough.
### May 26
Reviewed:
- house robber
- max sub array
I just reviewed house robber and max sub array today. Seems like even if I think I know the appraoch, there's lots of things coding-wise that trip me up. Definately need to review old problems from time to time.
Also, I only have a certain level of WILLPOWER everyday. It's best to split it between working on my business and leetcode. But I cannot neglect either one.
Todo:
matrix binary search:
https://www.youtube.com/watch?v=41ON2EghJi0
Try geometric problems:
https://leetcode.com/problems/generate-random-point-in-a-circle
https://www.youtube.com/watch?v=pvimAM_SLic
I swear memorizing these intereview problems is as dumb as memorizing prayers when I was a kid.
### May 25
Reviewed
- Longest Common Subsequence (25 min to reviewed approach, another 30 to code with minor mistakes)
### May 22
Reviewed
- Merge Sorted List (Iterative)
- Reverse LL (Iter)
Back from a 2-day break. Been thinking entrepreneurally since was getting burnt out from leetcoding.
I should balance out business and leetcode.
Tips for leetcoding:
- Use Forest app for timeboxing leetcode.
- Use space repetition to rework old problems in leetcode.
Other ideas:
- keep track of submission by problems
- track myshopify stores and copy products
### May 19
Studied
- Coin Change
- House Robber
Just looked at solutions and memorized/learned from them. Will review in a few days.
### May 16
Tomorrow or next week, need to review a few problems that I've "forgotten"
- Find Min in Sorted Array
- missing number
- reverse bits
- remove nth node from end of list
### May 15
Studied
- flood fill / num islands
Just finished studying the Flood Fill problem. I think I found a pattern/routine that works.
1) Find a new problem.
2) Understand the problem and think of initial solution for 5 minutes.
3) Look at discussion solutions
4) Implement the discussion solutions yourself without looking (you'll catch some small errors)
5) Redo problem a few days later.
### May 14
Studied (new problem or new algo)
- longest substring without repeating chars
- count ones in array
Reviewed
- numOnes
- merge sorted linked lists (recursive)
Tip from Nick White: don’t sit there and try and solve it. Just look at the solutions and learn
Let's see how many new problems I can "study" using this method. I can always go back to "review" the problems.
Quantity over Quality! FTW
Once you learn it, write it down in notes (ie: blog) and keep looking over it. Who cares if you're "memoroziing it". Just do whatever works.
Found this article on bit manipulation:
https://leetcode.com/problems/sum-of-two-integers/discuss/84278/A-summary%3A-how-to-use-bit-manipulation-to-solve-problems-easily-and-efficiently/207733/
Looking at a new algorithm (union find), from problem "number of islands". Time to add this to your "algo toolbelt"
https://leetcode.com/problems/number-of-islands/discuss/583483/Summarize-of-3-Types-of-solution-methods
Do these next:
- https://leetcode.com/problems/flood-fill/
- https://leetcode.com/problems/number-of-islands/
Found a backtracking algo:
https://www.thecshandbook.com/Backtracking
Leetcoding is starting to become fun. Considering the alternative is doing telus work. Both type of work is pointless but there's at least a greater chance of being rewarded with leetcode.
### May 13
Studied
- merge intervals
Reviewed
- reverse linked list (iterative)
- link list cycle (hashmap and floyd)
Today, had a lack of motivation. Did a new hard problem instead (merge intervals).
Should do 1-2 "hard" problems that will require studying and "review" the rest.
Also found out about https://interviewing.io/. It's free so try it out when you're more comfortable.
### May 12
today is pop quiz time
- BFS
- buy and sell stock
- deepest leaves sum (dfs)
- same tree
- symmetric tree
- invert tree
- validate bst (studied)
keep track of which problem is "studied" vs "reviewed"
### May 6
- Max Subarray
- Max Product Subarray
Having problem with product subarray, will do a dry run later
https://stackoverflow.com/questions/19148539/getting-range-of-max-product-subarray-using-kadanes-algorithm
Getting good at leetcode article:
https://heidi-newton.com/blog/getting-good-at-leetcode
### May 5
Setup algo blog at stevenc49.github.io to keep track of blind 100 curated questions and keep solutions to problems.
Also found out about https://learnxinyminutes.com/docs/python/
### May 1
- LCA binary tree
- symmetric tree
I am definately getting better at solving and reasoning thru tree problems. Sometimes you just need to work on other types of problems and come back to them later.
use multiple resources while studying answers:
- youtube
- LC discussions
- EPI
Goal right now is to try to understand and do as many questions as possible per day (increase learning rate)
Trying to take frequent breaks (playing / watching games between questions)
from blind:
"I'll give you a hint on career success: politics and expectations management."
"SAT tests get you into a good college, whiteboard tests get you a good job. Unfortunately that’s just how things work today"
Ref: https://www.teamblind.com/post/To-all-the-good-students-who-are-now-good-at-Leetcode-EraCXo5R
### Apr 30
- rotate matrix
- is tree balanced
- search sorted matrix
rotate matrix is turning into one of the more interesting and one of my fav problems, since transposing/flipping and for loop arguments are non-trivial
for array problems, stick to medium difficulty problems
### Apr 29
- validate sudoku box (validate box can be reduced to 1-d array with formula k = (i//3) * 3 + (j//3)
- spiral matrix
- rotate matrix (transpose and flip method) https://www.youtube.com/watch?v=SA867FvqHrM
watched nick white youtube on how he got into google: https://www.youtube.com/watch?v=nmf-oObylnk
- he said he grind pramp interviews, 8 per day for a month
- try to solve medium problems
- found a python concept tutorial list - https://www.hackerrank.com/domains/python
### Apr 29
- merge-two-sorted-lists (took a little more than an hour and had to rework it for edge cases) (ie: empty list)
- merge two sorted list recursive
Revisit Later:
### Apr 27
- group anagrams (solved in 15 minutes)
also can work on problems from app "Data Structures & Algorithms"
### Apr 24
- binary search
-
yesterday, i couldn't even write a binary search. it's embarassing for a software engineer. i need to get to a level that even i would approve of.
do quantity practice over quality, do as many varied types of questions and just look over solutions
try to replicate solving after even are seen
maybe make a space repetition app to redo problems that you were struggling with:
ie: had trouble doing "find min in sorted array but eventually understood the solution, next couple days, come back to it and redo it"
it's good to take a break and reflect on how you can improve your practice. today, after finishing binary search and search min in sorted array, i reflected on how i can "remember" these solutions and the idea of spaced repetition came in
also useful to reflect on problems that you wanted to solve, understood but didn't and want to retry
P.S. officially today, i've been practicing consistently for 3 weeks
### Apr 23
Retrospective
---------------
The goods / What has been working:
- stop working on Telus work and only focus on interviewing
- having a system / scheduled time / routine to work on it is key (get more hours in)
- posting to blog kinda helps
- journaling definately helps
- make studying convenient by making it easy to solve simple problems while watching TV
The Bads / What I need to work on
------------
- In addition to leetcoding questions, also need to:
- know python trivial concepts (list comprehension, lambda)
- geekforgeek problems (min and missing #) (not in leetcode)
- system design problems
- regex
- Need to know many different ways to solve problem
- recursion vs iteration
- xor in array/math problems
- different data structures/ time vs space complexicity
- keep log book and have a list of key interview problems to do before an interview (organized way to do long term studying)
Takeaways
-------------
- Don't complain about work
- Keep the leetcoding momentum going and refine study methods after this one bad interview
- Can think about introducing system for new goal (Chinese, Business, Cooking)
### Apr 22
I bombed the 1 hr coding interview at Softmax Data.
some questions were:
1) ways to reverse string (iterative, swap, recursive)
2) are two strings anagrams
2) [ i/2 if i>3 else 0]
3) lambda function to increase every elem in array
4 regex "vowels" | "come"
5) fib(3) giving [0,1,1]
6)
a = [6, 5, 4, 2, 6]
1 . continuous integers randomly sorted
2. min, max
3. missing -> 3
4. duplicate -> 6
#### Takeaways
- need to stop doing telus work and only focus on interviewing
- practice python syntax/concepts as well as algorithms
### Apr 21
Merge 2 sorted list is suppose to be easy but it's hard, come back to it later
#### Cramming Retrospective:
#### Good Parts
- you can get in the mindset of it and it will boost confidence
#### Bad Parts
- you'll forget how you solved a problem a week later
- Need to keep these skills sharp for lifetime and practice regularly.
- It's not possible to cram the learning into a few days or a week
### Apr 20
Studying in on hyperdrive now that I have a coding interview in 2 days.
I actually solved the hamming distance problem by myself (bitwise problem). new achivement
https://www.teamblind.com/post/New-Year-Gift---Curated-List-of-Top-100-LeetCode-Questions-to-Save-Your-Time-OaM1orEU
### Apr 15
- LCS
- BFS
Completely wrote a working BFS from scratch by myself. I have it memorized and ingrained from thinking about it for so long. Need to get as familiar as this with other classic problems (ie: longest common subsequence). Despite how non-intuitive it is.
got a bit complicated when i had to start keeping track of levels. apparently the technique i used to keep track is the same technique i used in java 4 years ago, it's just much more verbose. fuck java
---
The language matters, python has list comprehension which will make writing out the algo easier/faster.
### Apr 14
- longest common subsequence (DP)
If you need data to flow up, need to make use of return value. And usually post order (after null check)
Just watched the LCS solution [here](https://www.youtube.com/watch?v=ASoaQq66foQ). Will implement tmr.
### Apr 13
- deepest leaves sum (LC1302) (solve time about 1 hour with help)
- spent afternoon trying to figure out wrong error problem on sum even grandparents problem
Compare your python solution to [this](https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent/discuss/562939/Simple-recursive-python-solution) solution tomorrow.
find out why making it postorder instead of preorder made it work.
Work days should consist of 1-2 hours of applying to jobs, and 3-4 hours of leetcoding.
Leetcoding should focus on quantity vs quality so you can identify patterns. Don't be afraid to look up solutions. Like studying for linear algebra exam.
Ultimate goal is to get comfortable with classic questions in the shortest amount of time.
Looked at some solutions on leetcode and found some python best practices and shorcuts to make code look more clean.
An idea I got from a leetcode article is to start recording practice time in a spreadsheet like in [here](https://leetcode.com/discuss/general-discussion/571805/600-problems-in-one-year).
The columns are:
- problem topic
- problem difficulty
- time to find a solution
- time for implementation
- status (solved, not solved, solved with hints
### Apr 9
- missingNumber (XOR solution)
- twoSum ( O(n^2 solution)
- LC #1290 - binary to dec, linked list
I feel like the daily practice is showing some signs of improvement. I just attempted the twoSum problem (which is suppose to be a super easy problem), and I was able to get the Python solution on the first try. 4 years ago, I attempted the Java solution and got a wrong ansewr.
I also intuitively understood the XOR solution for the missing numbers problem.
Did the binary to integer linked list problem. It's an easy problem that made me think of fundamental binary properties and I had some small coding errors. But I was able to do it in about an hour. Not great but it's still in an afternoon. P.S. I checked the forums after I thought my initial process was non-ideal (using library methods).
Also read some reddit comments about leetcoding. TDLR: leetcode or die.
### Apr 8
Did leetcode #268: Missing number.
If it's an easy one, try to get it right and compilable on the first try. I did not because I made a small mistake, the for range loop is exclusive of the final number. It screwed up my calculations.
My new strategy now is to sort leet codes by acceptance and tags (ie: arrays, hash tables, trees, etc)
Just reviewed the solution for missing number and encountered the XOR solution. I still don't fully understand it intuitively but it's good to review other solutions and learn something new.
I'm feeling much more comfortable about doing these everyday. Maybe I won't feel comfortable going for an interview tmr but I am able to work on these regularly now. I've started building up that habit and ignoring Telus.
### Apr 7
Uploaded [Reverse Linked Listed Iterative Method](https://bubblesortblog.wordpress.com/2020/04/08/reverse-linked-list-iterative-method/)
If it's pointer heavy with lots of iterations, it's better to draw it out and redraw each iteration.
### Apr 6
Just do lots of problems, easy or not.
Do Reverse linked list today. You're bound to run into "end of list error"
Need to also be able to do easy questions when feeling tired.
### Apr 5
I was going entering some of my solutions into leetcode, specificailly the valid parenthesis problem and I realized my solution is just entirely wrong and does not solve the min stack problem correctly.
It doesn't even give the correct solution for "(]". My solution gives true and the answer is obviously false but I didn't see it.
I need to read the question more closely. Entering these into leetcode will help me know what to test for.
### Apr 3
New strategy - do lots of problems, quantity over quality
I've forgotten the general solution to problems I've done exactly a week ago. Need to review bubblesort.blog periodically.
Let's do LRU question today.
Been doing the LRU question and creating a doubly linked list. I definatley need to work on managinging my double pointers without having to check with the compiler and running it.
In a doubly linked list, always keep track of head and tail pointers
I managed to keep track of head and tail nodes after realizing I forgotten about them but it took me a lot of time. And I still didn't get to work on the eviction policy.
### Apr 2
- max depth of binary tree
- is tree balaned
After checking on the deepest node code, I should do this easy balanced binary tree checker question:
- https://leetcode.com/problems/balanced-binary-tree/
- https://leetcode.com/problems/maximum-depth-of-binary-tree/
I'm not sure why [this](https://leetcode.com/submissions/detail/318802426/) submission failed, but [this](https://leetcode.com/submissions/detail/318803393/) one passed.
Some tipes from reading interviewing articles:
"I found that it is extremely helpful for me to read solutions before attempting to solve the problems all by myself. "
-------------
I also just did the isTreeBalanced() problem but I really just rewrote a java solution that i rewrote 4 years ago.
I will need to actually drill down and run it step by step to really understand it and fully grasp it.
### Apr 1
I inputted the deepest node code into leetcode but I'm getting wrong answer. I'll have to look into this.
### Mar 31
- [Print Nodes K Distance from Root](https://bubblesortblog.wordpress.com/2020/03/31/print-k-distance-from-root/)
- [Deepest Node/Get Height of Tree](https://bubblesortblog.wordpress.com/2020/03/31/get-deepest-node-get-height-of-binary-tree/)
Tried the k distance from tree node problem. It involves a hashtable to go up the tree. I watched Back2BackSWE video but it doesn't make sense without code.
So I'm going to try a simpler version first where we get nodes at k distance from the root.
https://www.geeksforgeeks.org/print-nodes-at-k-distance-from-root/
------
I did the deepest node by myself and got it right after some debugging. Next time will work on leftmost deepest node.
### Mar 27
- LCA of binary tree
- serialize/deserilize binary tree
Today, I've added a blog post on LCA of binary tree nodes (without parent pointers or BST)
For the next few days, I should try out the other similar problems:
- 10.3) LCA of binary tree (done)
- 10.4) LCA with parent pointers
- 15.4) LCA of BST
Also watched a video on serializing/deserilizing a binary tree on Back2BackSWE. Will try to implement this.
Today, I actually implemented serialize and deserialize binary tree:
- [Serialize Binary Tree](https://bubblesortblog.wordpress.com/2020/03/27/serializing-a-binary-tree/)
- [Deserialize Binary Tree](https://bubblesortblog.wordpress.com/2020/03/28/deserialize-tree/)
### Mar 26
- validate sudoku
- LCA of binary tree nodes
Yesterday, I spent so much time trying to understand the sudoku solver. I think I should take a break from it. Maybe implement a sudoku validator first. The video from [Tech with Time](https://www.youtube.com/watch?v=lK4N8E6uNr4&list=TLPQMjUwMzIwMjBh1WFA0aDQLg&index=1) is actually very useful.
What I did learn was the x,y coordinate with col,row intuition.
Did LCA of binary tree node. Best explaination was from BackToBackSWE [here](https://www.youtube.com/watch?v=py3R23aAPCA).
The insight from this video is **"when dealing with tree recursion problems, always think of it from the point of view of a single node"**
### Mar 25
- sudoku solver
My goal today is to solve the sudoku problem with backtracking.
It's 2:30pm and I'm not making a lot of head way into this sudoku backtracking problem. Maybe I'll work on an easier tree problem for the rest of today.
This sudoku problem is helping me get 2d rays with row and columns straight though.
[This](https://www.youtube.com/watch?v=lK4N8E6uNr4&list=TLPQMjUwMzIwMjBh1WFA0aDQLg&index=1) guy does a good job at explaining how to implement a sudoku solver.
### Mar 24
Today, I tried implementing the solution for Min Stack and I wrote a blog post for it [here](https://bubblesortblog.wordpress.com/2020/03/24/min-stack/)
Writing the blog post is really just as hard because you will have to communicate clearly to the reader your logic. You'll also need to provide an example test scenario.
This is a good practice for communicating to the interviewer and I should do this with every problem I solve. I should get to the point where I can communicate the problem like this guy [here](https://www.youtube.com/watch?v=nGwn8_-6e7w).
As a side note, the explaination in EPI is exactly to what the BacktoBackSWE guy describes. So I should probably understand the solution before checking with EPI for the "cononical" solution.
The good news is that I'm building up the habit of practicing algorithms every day now. I should keep it up and pick another problem to work tmr.
I definately need to give studying algorithms as much attention as I've given work and studying investing as in the past. The key to this might be continous deliverate practice.
I need to remember that habit + deliberate practice = Mastery.
Same thing for Chinese.
### Mar 23
- Valid Parenthesis
- Min Stack
Solved Valid Parenthesis Problem by myself. My solution is posted on my new blog [here](https://bubblesortblog.wordpress.com/2020/03/23/64/).
However, the solution I came up with involves 3 stacks, each keeping track of a type of brace.
This can be improved with a single stack and detecing if it's an opening or closing brace. If it's an opening brace, we push to the stack, and if it's a closing brace, we pop from the stack. Try this solution tomorrow.
Today, we will try to get another problem in.
I also found this great youtube channel with a teaching style that I like:
[Back to Back SWE](https://www.youtube.com/channel/UCmJz2DV1a3yfgrR7GqRtUUA/videos)
Next question that I will attempt is the Min Stack problem. The min stack problem will run into the problem when you pop from a stack and you have to update the global minimum, the solution is to store the global minimum for each element in the stack. We can use another structure to do that, like another stack.
This solution is outlined [here](https://www.youtube.com/watch?v=nGwn8_-6e7w)
### Mar 20
- found [Techinical Interview Handbook](https://yangshun.github.io/tech-interview-handbook/best-practice-questions)
- read groking algorithms - chapter 3 recursion
### Mar 9
- reverse string using recursion
- reversed stack using recursion
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