Show HN: Every problem and solution in Beyond Cracking the Coding Interview

151 points by leeny 355 days ago | 105 comments

Hey HN, I'm Aline, founder of interviewing.io and one of the authors of Beyond Cracking the Coding Interview (the official sequel to CTCI).

We just compiled every problem (and solution) in the book and made them available for free. There are ~230 problems in total. Some of them are classics like n-queens, but almost all are new and not found in the original CTCI.

You can read through the problems and solutions, or you work them with our AI Interviewer, which is also free. I'd recommend doing AI Interviewer before you read the solutions, but you can do it in whichever order you like. (When you first get into AI Interviewer, you can configure which topics you want problems on, and at what difficulty level, and you can add topics and change difficulty levels as you go.)

Here's the link: https://start.interviewing.io/beyond-ctci/all-problems/techn... (You'll have to create an account if you don't already have one, but there's nothing else you need to do to access all the things.)

tanchaowen84 353 days ago |

To be honest, I’ve done quite a bit of LeetCode, and while it’s great for practicing algorithms and problem-solving, I’ve found that I rarely use these “fancy” algorithms in my actual work. Most of the time, what really matters is breaking down requirements into clear logic, writing maintainable and collaborative code, and communicating well with the team. These skills are hard to assess through algorithm-focused interviews alone. I really hope interviews can place more emphasis on practical engineering skills and real-world scenarios, which would be more valuable for both companies and candidates.

I’m currently preparing for interviews myself, so having access to high-quality, free resources like this is incredibly helpful. The AI interviewer feature, in particular, looks like it will be very useful for me. Thanks again to the author for making these resources available!

IshKebab 352 days ago | |

I think it really depends on the job. In most jobs I've had the algorithms rarely get more complicated than just avoiding accidental O(N^2). The sort of thing where juniors would do a linear search.

But I did have one job working on an AI graph compiler which used fancy algorithms all over the place. In practice though I found the space between "use the standard library" and "it's NP-complete; use heuristics" where the answer is "you can use this neat dynamic programming trick" is basically nonexistent.

quelup 353 days ago |

This is awesome. Just for awareness - I started going through the book a few days ago and there's a lot of other useful information outside of the LC style questions (e.g. what's actually important on a resume, how to realistically get your foot in the door with companies, etc.). Very data driven and comprehensive, so for me there's still a lot of value in the non LC parts of the book.

slackware_linux 353 days ago |

Incredible value here, thanks for sharing Aline. The book itself is a wonderful resource, not just for the technical chapters but the rest on resumes and reaching out etc. Even the technical portion provides the framework (boundary thinking, triggers, etc.) which is above and beyond basically any other resource online or in print. The AI interviewer is also super useful and the 'book' section of the site is very well put together. 10/10.

devnull3 353 days ago |

I wonder which other professions or trade ask people to perform infront of them in a simulated env as a filter criteria.

Actors for sure with auditions and maybe maybe chefs, male pornstars.

bespokedevelopr 353 days ago | |

Welders, millwrights, machinists, carpenters, lots of trades have qualifying interviews. I’ve taken written exams in interviews for machining and welding as well as hands on show me parts.

Not that I agree with absurd interview process of software development but they often see themselves more akin to attorneys than tradesmen. The difference being attorneys have to pass a bar exam and even trades have journeyman cards to provide credibility.

Software development has none of that. Real engineering has PE licenses but how do you achieve that in such a broadly scoped field of software development?

We either play the interview game or find a way around it.

devnull3 353 days ago | | |

I may have a outdated notion about the trades you mentioned, but I have seen an "apprentice" model a lot. I have seen it with a masonry where the experienced guy was bringing in his nephew and teaching him on the job. A lot of these trades are family owned and have seen taking in people based on someone vouching for the new guy.

Maybe this varies country to country. I have seen this in India and UK atleast.

In UK atleast there are trades like roofing, landscaping, exterior building cleaning, masonry, tree surgeon etc which I have seen them are mostly family based.

throwanem 353 days ago | | |

This trade has never helped itself by insisting on being taken for a profession. A lot of these kids have never known the joys of time and a half - or the incentive that gives management to try to have all their s—t in one sock, every once in a while, for a change.

jghn 353 days ago | |

> maybe maybe chefs

staging [1] is very much a thing for kitchen staff

[1] https://en.wikipedia.org/wiki/Staging_(cooking)

williamdclt 353 days ago | |

All sorts of managers and analysts have "project stages" where they have to analyze data and present a case study.

lapcat 353 days ago | |

Only male?

devnull3 353 days ago | | |

Males are under pressure to "sustain" it for 10-15 min atleast (with many people watching). For females, no such thing.

jwmoz 353 days ago |

'Principal' developer at my last place spent 100 consecutive days grinding leetcode. Shortly after had an interview where they made him do a leetcode test live and he failed it.

The whole thing is broken.

bungled 353 days ago |

Aline and team are doing great work. Love to see this!

dwightgunning 355 days ago |

Proud to have helped work on this. Happy to field any questions.

squeegee_scream 353 days ago | |

Why make the questions and AI interviewing free? This sounds too good to be true

leeny 353 days ago | | |

OP here. A few of you have asked why we made these problems free. The answer is twofold, simple, and maybe even a bit underwhelming:

1) We want people to read the book (To wit, we've also made 9 chapters of the book free: http://bctci.co/free-chapters)

2) We want people to use interviewing.io

In my career, I've written a lot of stuff about hiring, and I've shared a lot of interview-related materials (e.g., full length interview replays). I hate paywalls for content, and you probably do too... and I have never regretted making it free. In my experience, putting good stuff out there is the best way to market to an eng audience.

avinassh 353 days ago |

I would like to give a try, but I am getting this for India:

My name is Aline, and I'm the founder of interviewing.io. Thanks so much for your interest. It looks like you’re not in a country where we’re open for business yet, so we can’t create your account, but we’ll add you to our waitlist.

leeny 353 days ago | |

Odd, that shouldn't be happening. Can you please email support@ and say you're trying to access the book materials, and we'll investigate

joshdavham 353 days ago |

I think the reason leetcode problems are still popular is because they test whether a candidate is willing to work hard (‘grind’) on problems that don’t even matter. A lot like what actually goes on at a FAANG company.

hakkotsu 353 days ago | |

Hard disagree. At FAANG companies, working on problems that "don't matter" is exactly how you get a "Meets Some" or worse at your next perf review. These companies are obsessed with measurable impact - you need to show clear business value, user metrics, or revenue impact. Spend 6 months grinding on irrelevant work and you'll be on a PIP in a blink of an eye

slipnslider 353 days ago | | |

>working on problems that "don't matter"

Usually low level engineers don't have a say on what projects they get to work. They show impact by completing whatever projects were handed to them and hope/pray those projects take off and become visible to upper management and/or tied directly to revenue.

The grind aspect is real though. 99% of FAANG engineers aren't building the next google maps or LLM, they are doing Enterprise CRUD + ELT + jira tickets. Companies like Meta and Amazon have enormous workloads and thus a grinder is preferable.

After a few years of experience, CRUD and ETL can be done while sleepwalking so the only missing component is someone willing to grind, e.g. someone who will spend 100 consecutive days doing leetcode

dcsan 353 days ago |

This sounds like an amazing resource. What’s the rationale for making it all free?

diarrhea 353 days ago | |

> What’s the rationale for making it all free?

The writing is on the wall for Leetcode-style interviewing. The signal-to-noise ratio is diminishing in the age of AI (cheating). These sorts of puzzle challenges might no longer play a meaningful role going forward.

leeny 353 days ago | | |

I agree with what Mike said. We shared the content because we want people to read the book and to use interviewing.io... it's not because we've given up on it (see my longer comment about it: https://news.ycombinator.com/item?id=44136448). We have yet to see any real evidence that technical interviews are dying.

What is hopefully dying is companies asking verbatim LeetCode questions and candidates having to memorize a bunch of questions. We wrote this book largely because we wanted to teach people how to think. I knowing how to think is only going to get more valuable.

michael_mroczka 353 days ago | | |

Hot take from the author: This is a commonly repeated claim, but it’s probably not accurate.

It’s FAR easier for companies to stick with the interview process they’ve used for decades—just mandate in-person interviews again—than to reinvent the wheel with some new, unproven format. Sure, there’s a growing need to assess more than just DS&A in initial screenings, but let’s be honest: those interviews aren’t going anywhere.

The REAL reason to make these resources free? Because it’s not a competitive advantage to offer problems to practice. There are already tons of free problems online. The real value isn’t in giving people a place to do problems—that already exists. The value is in the book. If you already know enough to do well on problems without the book, then you shouldn't have to pay to practice it.

Peroni 353 days ago | |

Aline is a bit of a Hacker News legend. She's been active here for longer than most people have been working and when you see how she's built her product, it's plainly obvious that she legitimately understands and sides with the HN community.

I bet the genuine answer to your question is that she knows it's a resource that could help tons of people (at a time when tons of people need that help) and paywalling it means that it won't serve that same purpose.

notyourwork 353 days ago | | |

What does “side with the community” mean?

hintymad 352 days ago |

LeetCode-style interviews used to be an aptitude test, kinda like the weeder courses in college. Now that most people cram for them, they've lost their original purpose.

OnionBlender 353 days ago |

I wish I could just submit my solution and be told if it passes instead of dealing with the AI Interviewer. A lot of problems don't have a leetcode equivalent.

leeny 353 days ago | |

You can try to short-circuit the AI Interviewer by just entering your solution into the IDE. OR you can ask to end the interview, and then you'll get a link to the solution.

We built it this way on purpose, though... the intent is to mimic an interview and gently force you to talk through your thought process, not to have yet another LeetCode clone.

davidpfarrell 353 days ago |

How did your site know my first/last name when I gave my email address to create an account and clicked the confirmation link you sent?

leeny 353 days ago | |

We use Clearbit for enrichment: https://clearbit.com/ That said, all interviews on interviewing.io are anonymous unless you and your interviewer both explicitly opt in to unmask.

neilv 353 days ago |

Long ago, some dotcom, founded by students who'd never worked, used their own idea at the time about what software development is about (i.e., Stanford first-year CS problem sets). And since that company had a lot of money (for different reasons), a lot of wannabe companies tried to mimic whatever they did.

Today, CS student's idea of an industry interview has turned into an extortion racket cottage industry, with people not only selling ritual prep books, but now also selling mock interview rituals with techbros who got into the best-paying companies.

Youse has a lovely career potential; its would be a shame if somethings was ta happen to your job interview.

What more does it take to realize this is very time-consuming and expensive theatre, and terrible metric for hiring good software engineers.

And if you're an employer who doesn't care that students spend many hundreds of hours rehearsing for the interview theatre, to the exclusion of getting more experience building things, and that your interviews aren't actually selecting for software engineer aptitude, what happens when the hire takes that same misaligned hoops-jumping mindset to their work.

bko 353 days ago |

Thank you for this. Some people are critical of coding tests but I do this there is a point: namely to weed out people who can't code.

Am I the only one that interviewed people with lengthy resumes full of programming experience and when I asked them to do a simple programming exercise they fell flat on their face? I've seen experience in C, gave them take home two hour exam and they couldn't even get anything to compile. What he meant was he took a class a few years back.

You see it in other domains with extensive Excel experience and the guy gets hired and never heard of a vlookup.

I think some of the stuff is overkill but you need to select for people that know how to program.

I for one am glad they exist because I don't have a CS degree but learned on my own. I lucked into this profession through an online leetcode style screener and your book helped me immensely,so thank you

BeetleB 353 days ago | |

> namely to weed out people who can't code.

You don't need Leetcode style tests to weed those out. Much simpler problems will do it.

stmw 353 days ago | | |

I think we may have disagreement on what Leetcode means in this context -- but it has to be complicated and varied enough that simply memorizing the solution is not sufficient. It being interesting is a bonus for other parts of the technical interview.

stmw 353 days ago | |

You are not the only one. I've interviewed probably 1000's of engineers and it is striking how often one runs into candidates that can't code... or ones that operate at a level far below what you would expect.

bornfreddy 353 days ago | | |

Meh. There is a world of difference between 1337code problems and anything one encounters in the real life. Judging someone by that 1h slot on a domain they haven't worked on for decades doesn't paint the right picture. It does tell a lot about the priorities of the company though, so there's that.

AndrewStephens 353 days ago |

Cracking the Code Interview is a great book and excellent for practice and brushing up. But I have found leet-code questions terrible for actually interviewing candidates. A lot of them boil down to whether the candidate knows the specific trick or can regurgitate the memorized solution.

(Maybe I am just bitter because I have more than once bombed a leet-code interview myself)

I interview a lot of people and my go-to coding question is actually a pretty simple question that might be found in a 2-year coding course. What I am looking for is production ready code, good error handling, tidy design, and understandable code. All things that leet-coding specifically discourages.

QuadmasterXLII 353 days ago |

Hot take: these interesting, contained problems that you really can solve on your own are a finite resource, and every time you read the solution to one you permanently deplete that resource for yourself.

stuartjohnson12 353 days ago | |

Hotter take: manipulating intelligence signals is more effective for achieving things than doing things to improve intelligence.

commandlinefan 353 days ago | |

You can hedge against that by trying your best to solve the problem once before reading the solution.

constantcrying 353 days ago |

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