A Plan to Win your Next Interviewing Battle
In October 2018 I quit my engineering job at Yelp. The 6.5 years I spent working there were amazing in many ways but it was time for me to move on. The purpose of this post is to reflect on my interviewing experience (all of it: preparation phase, interviews, post-interview communication) and write down details/tips. Hopefully it's useful to somebody out there (you?) but if nothing else it'll surely be useful for me next time, when I'm on the job market again.
Get cozy: this is a long read. Table of contents below:
- 1. Lead Generation
- 1.1 Build your resume
- 1.2 Job applications
- 1.3 Invest in your network
- 2. Interview preparation
- 2.1 Hard Skills
- 2.1.1 Review Computer Science Fundamentals
- 2.1.2 Pick a language & stick with it
- 2.1.3 Practice & improve your coding skills
- 2.1.4 Your mistakes are your best assets
- 2.2 Don't forget about "soft" skills!
- 2.2.1 Questions to prepare for
- 2.2.2 Tips for good long-form answers
- 2.2.3 Craft & refine your story
- 3. Interviewing tips and tricks
- 3.1 The interaction Log
- 3.2 Planning
- 3.3 Tips on video or phone interviews
- 3.4 Tips on on-site interviews
- 4. Interviews are over. Now what?
- 4.1 Making the most out of your recruiters
- 4.1.1 Email tips
- 4.1.2 Expectation management
- 4.1.3 You have more power than you think
- 4.2 Offer, compensation and negotiation
- 4.3 Making a decision
- 4.3.1 Evaluating your future manager
- 4.3.2 Interviewing teammates
- 4.3.3 Gauging work culture
- 4.4 Reflection on interviewing pipelines and processes
- 4.4.1 Automatically graded coding test
- 4.4.2 Realistic interviews
- 4.4.3 No-surprises interviews
- 5. A final offering: my personal TODO list
1. Lead Generation
First things first let's talk about how to get an interview. Three main parts: your resume, your network, and other people's networks.
1.1. Build your resume
There are a lot of strong opinions out there about what should and shouldn't go into a resume. My experience, both as someone who screened hundreds of resumes and as someone who applied to tens of job postings, is that resumes are at best neutral. If you have an awful resume, you probably won't get responses when applying. If you fix your resume, you'll probably get responses and that's the sweet spot. If you build an amazing resume, you'll also get responses, but it won't help you in any other way.
To be effective with your time, do not spend too much time on perfecting your resume. Give it the attention it deserves and move on quickly. It's much better to spend your time on generating leads, finding referrals, or brushing up on your CS fundamentals (more on that later).
That being said, here are the cardinal resume sins in my book:
- Proprietary formats: not everyone has Microsoft Word installed! Stick to PDF.
- Grammar or spelling mistakes: Given the small number of words on a resume, seeing a grammar or spelling mistake is a huge red flag.
- Pretentious labels: "ninja", "hardcore", "guru" are an immediate turn-off
- Dead links: if it's on your resume, it should work!
Some other tips:
- Keep it short! People reading resumes have a limited amount of time (typically 30 seconds to 1 minute per resume)
- Check your online presence (Google yourself!). Time to freshen up your personal site if you have one, make sure to dust off old-looking things in your public Twitter, cleanup your Github, etc.
1.2. Job applications
Once you have a resume and a web presence it's time to actually apply for jobs! As a software engineer you have a ton of options:
- Passive recruiter outreach: we've all received cold emails from technical "sourcers" (recruiters). They feels like spam. Most of the time they are. Regardless, I save the interesting ones into a folder. When my job search started I reached back out and I got interesting leads/contacts from this.
- Referrals: by far the most effective lead-generation tool if you're already working as an engineer. Hit up your friend list on Facebook or lookup people on social media (Twitter, LinkedIn). Most of the time companies have referral programs in place: if you get the job, the person referring you gets a cash reward. By referring you they're doing you a favor, but you're potentially doing them a favor if you land the job! Win-win.
- TripleByte (this is my own referral link. Here is a link without affiliation if you prefer): I've used their service successfully and can't recommend it enough. If you're accepted in their program you'll get to go directly on-site with companies interested in your profile. That's a huge potential time saving! If you don't get accepted it's still good practice to go through TripleByte's interviews. Treat it like training. It's 100% free to apply.
- Underdog.io: geared towards finding small startups. I personally haven't had much success with this but the service seems high quality with quite a lot of startups to choose from.
- Hired: surprisingly effective for me. Maybe that was luck? Many companies reached out. High-quality interviews came from this platform.
1.3. Invest in your network
It should be clear from the list above: your professional network is going to be a strong asset when looking for a job. A "professional network" doesn't have to mean colleagues in the strict sense. Think wider.
- For students: think professors, TAs, classmates.
- For engineers at small startups: think contractors, support people from vendors, people you've met at conferences or meetups.
- For engineers at bigger companies: all of the above plus your colleagues if you're comfortable opening up about looking for new opportunities.
I've gotten my first internship at Google thanks to a well-connected professor of mine. The timing worked out. Yes I got lucky. What I want you to consider: please take more chances. Go talk to people around you even when you think the odds aren't in your favor. You only need one of these to work out to make it worth your while!
2. Interview preparation
In this section we're going over what's most important: preparation before your
2.1. Hard Skills
2.1.1. Review Computer Science Fundamentals
I've written about this previously: I really don't know why Computer Science Fundamentals are such a big focus in our industry. The reality of interviewing is that they are the most common denominator across companies, roles, and level of experience. Love it or hate it, studying CS fundamentals is the most efficient thing you can do if you are prepping for technical interviews because 1) it's probably been a while since you've done anything with binary trees or linked lists and 2) these questions come up all the time.
So what exactly is considered "CS fundamentals"? Here's my take on it:
- Big-O analysis
- Hashmaps: implementation (be able to implement this data structure from scratch in your language of choice), runtime (know the main operations and their big-o complexity)
- Dynamic Arrays: implementation, runtime
- Linked List: implementation, runtime
- (Binary Search) Trees: implementation, runtime, algorithms to traverse them (BFS, DFS)
- Sorting Algorithms: quicksort, bubble sort, insertion sort, heapsort. What to study: implementation, runtime, worst case, best case. Bonus: know which type of inputs performs best/worst on each of the different sorting algorithms.
- Graphs: representations in memory and basic algorithms for traversal (BFS, DFS should be a no-brainer to code!)
- (Bonus) Tries, Bloom Filters: no need to know the implementation. Look into their runtime and main advantages/trade-offs.
- (Bonus) Dijkstra and/or A* since it tends to underpin a lot of coding questions about graphs.
2.1.2. Pick a language & stick with it
"Coding interviews are basically glorified IQ tests". That's something I've heard directly from an interviewer. I think it's an accurate statement.
The good news is that no IQ test is perfect and you can "game" the system provided that you know what's expected of you. What it comes down to is: save as much brain power as possible. The more resources you have to think about the problem itself the more likely you are to succeed in interviews.
Picking a language that you're fluent in saves you a lot of mental energy. Instead of thinking about the best way (or how) to write a class, or trying to avoid off-by-one errors, practice ahead of time so that a high percentage of your time is allocated to thinking about the problem during an actual interview.
Here is a non-exhaustive list of things to practice applicable to Python (my interviewing language of choice). If you pick another language the specifics between parenthesis vary but the concepts remain the same:
- Basic "closed" loops (
for i in range(begin, end)). Make sure you won't get surprised by
endis exclusive so to loop through with i taking values 1, 2, and 3:
for i in range(1, 4)
- Backward loops (
for i in range(end-1, begin-1, -1))
- "open" loops (
while some_condition). Make sure you know how to terminate loops with
break. Make sure you're familiar with
continueand its behavior
- Class syntax (class declaration,
__init__, magic methods, inheritance)
- Code execution (memorize
if __name__ == "__main__"for instance)
- Assertions (use
assertand use assertion messages!)
- (Python specific) List comprehensions: don't overuse them, but definitely know how they work and where to use them (typically when you want to do complex destructuring or filtering). They can save a ton of time
- (Python specific) Pro-tip: building dicts programatically! This can be done
with list comprehension:
d = dict([(k, v) for k, v in ... if ...]
- (Python specific) Pro-tip: use
defaultdict! This will avoid if statements to handle cases where keys aren't initialized (useful in the case when you want to count things or compute averages, frequencies per key, etc)
2.1.3. Practice & improve your coding skills
You'll be judged on more than just pure "coding" during a coding interview. Whether they're aware of it or not, interviewers will grade you based on:
- How quickly you spot mistakes on your own
- How quickly/accurately you can react to a hint when given one
- How well-spoken you are and how well you understand what they're saying (yup, native English speakers have a huge advantage here!)
- How neat your handwriting is and how well you manage the space on the whiteboard. Or if the interviewer is okay with a laptop: how fast you type, how familiar you are with the editor you use
- How positive you are (are you smiling? Friendly?)
Because there are so many things you'll be judged on aside from coding, don't fall into the trap of practicing on too many different problems. What I suggest instead: pick a problem and try to solve it in different settings, ideally a few days apart.
First practice it in the most comfortable setting: with your favorite IDE/editor. This forces you to focus on the problem itself. Then practice solving the same problem on a Google doc (or somewhere with no syntax highlighting). This forces you to focus on language constructs and syntax that you might be unfamiliar with. Copy/paste the code you wrote into your editor/IDE only once you're damn sure it compiles/run. It probably won't and that's fine! Make a note of the mistakes (more on this in the following section) and come back to your Google doc to re-examine your code. Do this until your code runs! Then solve the same problem on paper or a whiteboard to practice handwriting and space management.
Finally, if you're interviewing with a company which does whiteboard coding only (Google, Facebook, Amazon, probably others -- unfortunately!) try solving a few problems on the whiteboard first while talking out loud as if a person was listening and judging. And time yourself. Afterwards, copy what you wrote on paper or whiteboard and type it in mindlessly in an editor/IDE. Does it compile/run? Does it do what you want? Make note of the mistakes and repeat. Speaking of mistakes...
2.1.4. Your mistakes are your best assets
Something worth buying: a nice notebook and a pen that you like. It's not that expensive and it should help you a ton. This notebook should be your "mistake" log. Every time you screw up (you expected your recursion to finish but it doesn't, you made a silly syntax error, maybe your loop was off by one), log that into the notebook and move on.
Over time more mistakes will pile on. Regularly review the contents of your
notebook to spot trends: are you making many syntax errors? Do you always
forget to declare variables when they're in a
for loop? What sort of problems
are causing you the most grief?
I reviewed my notebook once a week and before each interview. This helped me tremendously. Why? Awareness is more than half the battle. There are hundreds of potential mistakes people make when coding but you have your own special weaknesses.
Being aware and actively on the lookout for specific types of mistakes drastically reduces the chance of making them. With a bit of training you'll spot them as soon as they're on your computer screen or whiteboard. Eventually you'll probably eliminate them in your mind, which means entire classes of mistakes/bugs are gone!
2.2. Don't forget about "soft" skills!
This was prompted by my preparation for Amazon's and Facebook's interview processes. Soft skills are really important. Most candidates underestimate the importance of soft skills in coding interviews and do not prepare effectively as a result. That's good news for you: preparing just a little bit puts you ahead of the pack. It's definitely worth investing an afternoon or two don't you think?
2.2.1. Questions to prepare for
Here's a list of questions/prompts to prepare. I gathered this list as I went through interviews. Being prepared for those will get you 95% of the way there and you probably won't feel surprised by any "soft" questions anymore:
- What brings you here? (most common soft question by far)
- So what don't you tell me about yourself? (probably second most common!)
- Tell me about a time when you were faced with a problem that had a number of possible solutions. What was the problem and how did you determine the course of action? What was the outcome of that choice?
- When did you take a risk, make a mistake, or fail? How did you respond and how did you grow from that experience?
- Describe a time you took the lead on a project.
- What did you do when you needed to motivate a group of individuals or promote collaboration on a particular project?
- How have you leveraged data to develop a strategy?
- What were some of the best things you've built?
- What are you proud of?
- What could you have done better?
- What were some excellent collaborations you've had?
- Tell me about a time when you advocated for and pushed your own ideas forward despite opposition?
- How do you deal with conflict?
- How do you like to give and receive feedback?
- Tell me about a time when you had to complete something in a limited amount of time of with a limited amount of resources
Finally, prepare a big list of questions for non-technical folks and technical folks. You should have enough questions to last a whole lunch break with either type of people (I've found that 10 questions is generally more than enough).
2.2.2. Tips for good long-form answers
These tips (in italic) are taken straight from Amazon's "in person" interview preparation guide that you can find here:
- "Ensure each answer has a beginning, middle, and end. Describe the situation or problem, the actions you took, and the outcome". More specifically for engineering stories I've found that it works best to go top-down. Start by explaining the broad context of your work, what you were tasked with, then dig into the problem you want to discuss.
- "Prepare short descriptions of a handful of different situations and be ready to answer follow-up questions with greater detail. Select examples that highlight your unique skills". That's gold. It's basically saying: chop it up! Don't spill your whole story at once. Being able to deliver it piece-by-piece is going to help you in behavioral interviews because small pieces are generally composable and reusable.
- "Have specific examples that showcase your experience, and demonstrate that you've taken risks, succeeded, failed, and grown in the process". That's just another way of saying that what happens doesn't matter. Usually in behavioral interviews the interviewer is interested in how you choose to react to situations and what you learn from them. So instead of stopping at "we disagreed on how to use Jira", talk about what task management meant to you, how disagreeing led you to reconsider your position on what that meant at the time and what it means to you now (assuming that disagreeing on Jira processes triggered that line of thought. Don't ever lie! Interviewers have a pretty strong bullshit detector)
- "Specifics are key; avoid generalizations. Give a detailed account of one situation for each question you answer, and use data or metrics to support your example". That's also extremely important. Don't beat around the bush by being generic. You may be in a behavioral interview but you're an engineer still! Your interviewer will ask you for specifics if you don't provide them in your first answer. Your time is limited so it's best to give those ahead of time.
- "Be forthcoming and straightforward. Don't embellish or omit parts of the story". Yup. Don't lie please.
2.2.3. Craft & refine your story
This has already been mentioned in the previous section but it's worth calling out on its own: you should have an answer to the dreaded, classic questions: "What brings you here?" and "So why don't you tell me about yourself?".
This deserves special attention. Look at yourself in the mirror, ask a friend to tell you what they think, and perfect your answers until you feel confident.
If you're transitioning from one role to another (say backend to iOS development, or from marketing analytics to engineering), it's worth crafting a compelling story and be ready to answer "so why did you choose to switch from X to Y?"
Important note: crafting a story is different from lying. Don't say things that aren't true. Don't try to embellish what happened. Do think about where you're going to start, what you want to convey, and how: what do you want the listener to take away from your answer to these question?
3. Interviewing tips and tricks
3.1. The interaction Log
I kept a log of all the communications I had with every company, regardless of the stage. Here's an exerpt for a company didn't move forward with:
I had to redact a lot of it, but the general structure holds. Some things worth pointing out:
- "priority" maps to how badly I wanted that job:
- P0: I’d take a pay cut to work there
- P1: Given a good offer and a decent team I’d work there
- P2: Given an excellent offer and the right team, I’d work there
- P3: Good for training/exploration only, would never accept an offer unless it’s truly exceptional
- As you can see I had this in a Google Doc to be able to access it from anywhere (esp. from my phone -- this came in handy more than once!), and color-coded by priority.
- Putting random TODOs in there is also useful
- I initially started with a spreadsheet but I found that freeform text worked best to jot down quick thoughts during a call (that document was my main medium to take notes during recruiter calls)
- It's important to log the date!
- Write down as much as you can write after the call, interview or interaction happens.
- Treat this as an append-only log. Don't erase anything! This will come in handy later on when you're trying to make a decision, and will keep you honest
Planning is one of the most crucial aspects of a job hunt. Put everything in one calendar (I used Google Calendar) and be very diligent about keeping track of who is supposed to call you when. Set reminders to prepare for the call, and take notes!
Another tip that I can give here: try your best to line up interviews that you care about least first, and the ones that you care about most last.
3.3. Tips on video or phone interviews
- Get familiar with Coderpad, play with the interface.
Python pro-tip: you can drop a debugging statement, it'll work just fine
import pdb; pdb.set_trace();)
- Don't use the built-in microphone from your laptop. Get a headset! If you have one already great. Otherwise, pick a cheap one from Amazon. This helps your interviewer hear you better and this helps you hear your interview better. Win-win.
- Get a blank paper sheet and a pen near you to write things down. If the interviewer hears you typing they'll think you're cheating.
3.4. Tips on on-site interviews
- Aim to be 15 minutes early. Most of the time you'll actually be early. That's a perfect opportunity to skim your "mistakes log" one more time before starting your interview day and get in the mindset.
- Print your resume, just in case. Even in this day and age it came in handy a couple of times to have a printed copy of my resume ready to show.
- If lunch is provided: eat light! There's a dip in energy when digestion kicks in. Eating light helps with this.
- In a similar spirit: try to limit your sugar/caffeine intake to a minimum to prevent acute spikes/dips of energy.
- After a full round of on-site interviews it's really tempting to relax. Instead force yourself to write down notes about what happened. What were the names of your interviewers? What were their positions/teams? Would you like to work with them on a daily basis? Which questions did they ask? How do you think you did? What did you think of the culture overall? This is your chance to be honest and record your unbiased opinion. Your future self will thank you. When offers are on the table it helps to have a written record to eliminate bias.
4. Interviews are over. Now what?
So you've gone through your interviews and hopefully have gotten far enough in the process that you're stressed and unsure about what to do next. Negotiating your salary and committing to a decision is no easy task. Below I'm laying out my experience with both of these. I'm offering some of my personal criteria to evaluate each company and some tips about offer negotiation. Ready?
4.1. Making the most out of your recruiters
4.1.1. Email tips
- Generally, be as concise as possible. Stay to-the-point while staying cordial.
- Be aware that your recruiter is juggling between multiple candidates. Keep your emails short and precise. Instead of saying "When are you free to chat this week? I'm free Monday or Tuesday", say "I'm free to talk this week on Monday from 12pm to 2pm or on Tuesday from 2pm to 5pm (all times PT). Would this work on your end?". This saves one email round-trip.
- State time zones. Always.
4.1.2. Expectation management
Be as transparent as you can about your timeline from the beginning. In my experience there isn't much benefit to information asymmetry. Recruiters are your best allies: the more they know about your particular set of needs, the better off you'll be. Why are they allies? They usually have financial incentive to meet hiring targets. You get in the door, they get paid, both of you are happy!
Along the same lines: be very diligent about informing your recruiter(s) about changes along the way. I found that having a list of names/emails for each company helped immensely (you don't have to think hard about who to email when something changes if you have one place where everything is). I kept track of this as part of my big "interaction log" document (described above).
4.1.3. You have more power than you think
You have a lot of power as an engineer looking for a new job. The market right now (2018-2019) is as good as it gets. Don't be a jerk about it (obviously!) but be aware that you can ask for a lot. Asking nicely will get you most of what you want, so remember to ask! This is especially important when it comes to...
4.2. Offer, compensation, and negotiation
A couple of links on the subject of negotiation:
The above resources will do a far better job than I can at teaching you about salary negotiation. A few things I'd like to stress:
- From personal experience: "never be the first to give a number" doesn't work well. I found that asking for an aggressive target works better. The best thing you can do is ask a few people who work at the company for compensation ranges and shoot slightly above.
- About competing offers: their importance really depends on companies. Some will budge quite a bit if you tell them you have competing offers. Some only budge if the offer is from a big name such as Facebook or Google. And some don't respond at all. So I wouldn't attach too much importance to competing offers. It's way more important to crush your interviews and ask for the right compensation.
- Remember: your recruiter is your side! They may have an incentive to make you sign with the minimum salary possible, but at the end of the day what matters to them most is that you sign at all!
4.3. Making a decision
There's a ton of criteria to evaluate when picking a job. It can get emotional and overwhelming so I've used this spreadsheet to be as rational as possible. Columns are criteria you care about (compensation, quality of manager, technical stack, etc). Each of them is of a certain importance to you and that's reflected by a weight (from 1 to infinity). Rows are companies you're considering, and each company gets a 0-10 score for each column. The rightmost column displays a weighted sum to help you compare easily and see which company comes at the top.
What should you care about even? What should the weights be set to? Well that's personal. But here's my opinion: a job is mostly made of people. Your manager and teammates are crucial. You're going to spend 40hrs+ per week interacting with them. Make sure you consider this very carefully. A great compensation and a kick-ass brand won't save you from a lousy manager or a toxic team. So weight this accordingly.
Another piece of advice that I've heard from mentors and colleagues: focus on learning and growth early in your career. Weight compensation lightly if that's possible for you to do.
Now how do you actually go about evaluating your future company, manager, or teammates during your interviews? Obviously it depends. Teammates, managers and engineering cultures are all made of people. A manager who feel awful to me might be a great fit for you. Below are my personal criteria to gauge these things. I encourage you to develop your own and write them down.
4.3.1. Evaluating your future manager
I hate micro-managers. The absolute worst manager would be one who's constantly looking over my shoulder and my teammates'. In a manager I'm also looking for somebody who's 1) cool-headed and 2) who can be a good "shield". Concretely this means somebody who'll fight to keep the team focused on a minimum number of projects, and who will switch priorities only when absolutely necessary. The third thing I'm looking for: someone who can coach, be understanding, and listen.
It's hard to probe for these things directly but I'll tell you my personal opinion on what you can look for in an interview setting.
The person you are talking to is more likely to be a bad manager if they...
- have a tendency to talk a lot
- get animated easily, are overly enthusiastic
- interrupt you at any point
- have a tendency to focus the discussion instead of opening it up
- did a lot of impressive technical work in the recent past
- are first-time managers (sorry, I have to put this in here!)
And here are some positive attributes. The person you are talking to is more likely to be a good manager if they...
- ask good questions
- look interested in the answers. Bonus points for taking notes during interviews
- tend to stay high-level
- are terse/concise when they speak
- feel underwhelming, not that impressive
- smile, are positive
- get personal and tend to ask questions "out of the blue" to open up discussion. For example, during your interview: "so who got you interested in computers in the first place?" "have you thought about technical leadership? Is that something you'd like to do down the road?", etc.
- have a long history of being managers. Bonus points if they've done it at multiple companies. Extra bonus points if they have a non-CS background.
4.3.2. Interviewing teammates
Teammates are a bit easier to gauge. What makes an ideal teammate to me? Somebody who's willing to spend time to show me the ropes and obscure tips to boost my productivity. Somebody who's willing to say "I don't know" and learn from me when I can teach them something they don't know. Somebody who'll happily take ownership of an idea that isn't their own. Somebody who says "hi" when you cross paths in the office or outside (a nod of acknowledgment and a smile goes a long way). Somebody who admits to making mistakes without trying to cover them up.
How to evaluate this when you're talking 1-1 to someone? The person you are talking to is likely to be a bad teammate if they...
- interrupt you at any point
- are easily distracted and don't pay attention to what you're saying/writing
- take the interview process or themselves too seriously
Conversely the person you are talking to is likely to be a good teammate if they...
- smile; are enthusiastic when they talk about their job and the team
- are more interested in hearing about your technical expertise than explaining theirs or the team's
- are able to give you useful hints (use the power of hindsight here. Sometimes the hint won't feel helpful on the spot, but you'll see its value later on. That's fine and correlates with good teammates in my experience)
- tend to explain the context of the problem or answers they're giving
4.3.3. Gauging work culture
Work culture constantly shifts within a company. Very often it's not consistent across teams. Heck, you may change and consider a culture "cool" now and "awful" in a few years. That's certainly happened to me.
At the time of writing my ideal work culture offers a good work-life balance. I want to be able to sleep and spend weekends 100% disconnected when I feel like it (if I'm on-call, fine -- that's a planned thing). I value work cultures with an emphasis on social good will (help each other, be positive, teach/learn from your neighbors, etc), (self)-education and transparency. See this post for my values overall.
Now onto how to evaluate this in an interview setting. Some of these criteria are self-explanatory; others require that you ask specific questions to your interviewers. Most interviewers reserve some time at the end of their interviews specifically for this. An immense majority of recruiters are be happy to set up additional calls if you didn't have time to ask all your questions. Without further ado, the company you're interviewing for is likely to have a bad culture if:
- there's only White/Asian males in their 20s/30s on your interview panel
- a large part of the team-building happens outside of work hours ("the team generally hangs out on Friday nights" -- Ugh. Does this mean if I don't come Friday night I'll miss out?)
- your interviewers are intimidating (putting pressure on instead of trying to take it off you)
- there are very few senior engineers and a lot of first-time managers
- the leadership team has seen a lot of departures in the recent past
- people pride themselves on working long hours or not taking vacation
Conversely what I'm looking for; the company you're interviewing for is likely to have a good culture if:
- Teams are fluid -- this means knowledge gets around the company and fewer silos exist
- There's a default flexible work arrangement (everyone can choose to work from home on given days)
- There's an established on-call rotation -- if there's a rotation, there's usually runbooks, calendars, and incident response procedures!
- No code goes to production unless reviewed (cowboy shipping is usually indicative of a brash engineering culture)
- The company has a good number of non-engineering employees. In my experience this helps balance egos and somewhat limit the nonsense sometimes generated by engineering-first cultures. That's only valid if non-engineers employees interact meaningfully with the rest of the company! Say if there's a large number of sales people in a different building, or a large number of warehouse workers in a different city, the impact on the work culture you'll experience as an engineer is zero...
4.4. Reflection on interviewing pipelines and processes
I've been through a few interviewing pipelines recently. Below are some really good ideas I've seen implemented in the wild. If you're a recruiter or an engineer in charge of some part of a recruiting pipeline, this section is for you!
4.4.1. Automatically graded coding test
This saves a ton of time, and can often replace an expensive and biased (because it involves the judgment of a single person) "phone screen" or "video call" with an engineer.
While we're on the subject of coding tests: some companies opt for a "take home assignment". In my experience this can be a good idea but make sure to set a strict time limit (target under an hour -- if longer than that a lot of good candidates will lose interest) and grade the test based on objective criteria established ahead of time.
4.4.2. Realistic interviews
During on-site interviews: focus on what's difficult to assess! In my opinion, on-site interviewers should steer clear of coding questions as much as possible. The best way to know whether a candidate would be good to work with is to simulate working with them! Try pair programming. Try whiteboarding systems. Try simulating the experience of finding/fixing a bug together! How about reviewing and discussing a piece of real code?
Quite frankly I don't understand why this isn't more common. The fact that Google, a company I deeply admire for their ethos and ability to innovate, sticks to whiteboarded algorithm questions (for the most part...they do have design questions for senior engineers though) is baffling.
4.4.3 No-surprises interviews
Interviews do not have to feel like taking an exam. Why not communicate the names of the interviewers, their teams, and rough subjects of the interviews ahead of time? When I'm working on something new at work or when I'm called to go to a meeting with a new group, I'm given notice on the agenda and topic. I see no reason why interviews should be different.
A bad schedule example:
- 9am: meet and greet
- 9:15am-10am: coding interview
- 10am-10:45am: coding interview
- 10:45am-11:30am: design interview
- 11:30am-12:30pm: lunch break
- 12:30pm-1:15pm: coding interview
- 1:15pm-2pm: coding interview
- 2pm-2:15pm: wrap up
A better example:
- 9am: recruiter will meet you in the lobby and walk you to your room for the day
- 9:15am-10am: coding interview with Sarah, engineer on the Payments team. This will focus on tree-like structures and performance
- 10am-10:45am: coding interview with John, senior engineer on our Infrastructure team. Focus will be on caches in the context of web applications as well as code quality
- 10:45am-11:30am: design interview with Jane from our data science team. You'll get to talk about data pipelines and associated technical trade-offs
- 11:30am-12:30pm: lunch break
- 12:30pm-1:15pm: coding interview with Noah, engineer on the Platform team. This interview will focus on finding a bug in one of our internal web frameworks used in our microservices fleet
- 1:15pm-1:30pm: wrap up with your recruiter, to shield questions and escort you out of our HQ
Sure candidates will study ahead of time. But that a good outcome! I'm betting that this would lead to higher-quality interviews overall and a better experience for both candidates and interviewers.
5. A final offering: my personal TODO list
To conclude this blog post (that's the last section! Good job making it this far!) here is the precise list of things I did to prepare myself for interviews at the end of 2018. I interviewed for backend/full-stack software engineering positions, with Python as my language of choice whenever coding was needed. This list may not be as useful if you're interviewing for something vastly different.
Below I graded each item from 1 to 10 with the power of hindsight ("Looking back, was this item useful for my interviews?").
Items related to interview prep in general:
- (4) Watch What to Expect During the Recruiting Process -- Facebook specific, but generally applicable
- (10) Go through InterviewCake. Yes it's paid content but it's worth your money. Especially:
- (4) Read through Google's interviewing guide
- (5) For Amazon application, review https://www.amazon.jobs/en/landing_pages/in-person-interview
- (8) Oldie but goodie: read Get That Job At Google by Steve Yegge
- (10) Prepare answers to behavioral questions (see "Softskills" above)
- (4) Watch How to Crush Your Coding Interview -- Facebook specific, but generally applicable
Items related to CS fundamentals:
- (4) https://mrpandey.github.io/d3graphTheory
- (10) How are hashmaps implemented?
- Array of linked lists. Each list maps to a "bucket"
- To store a key/val pair, hash the key, then store it in a linked list starting at "key mod num(buckets)"
- (1) ETAGS (https://en.wikipedia.org/wiki/HTTP_ETag)
- (10) Binary search trees, how to implement/use them?
- (8) What are balanced trees?
- (10) Hash table implementation. Big-O to insert/update/retrieve values?
- (10) Binary Search trees
- implementation in Python
- Big-o for insertion, deletion, and searching
- (6) Implement BST's delete() method
- (10) Linked List
- Implementation in Python
- Singly vs doubly
- Big-o for insertion, deletion, and retrieval by index
- (8) Review how Dijkstra's algorithm work
- (8) Implement Dijkstra's algorithm in Python
- (8) Review A* algorithm (path finding)
- (8) Read chapter 3 of skiena's algorithm book
- (4) Read http://web.stanford.edu/class/cs166/lectures/05/Small05.pdf
- (10) Breath-first search and depth first search algorithms in graphs/trees
- (10) Graph questions to master:
- Is there a path between two nodes in this undirected graph? (-> run BFS or DFS)
- What's the shortest path between two nodes in this undirected, unweighted graph? (-> run BFS!)
- Can this undirected graph be colored with two colors? (-> run BST!)
- Does this undirected graph have a cycle? (-> run DFS!)
- (10) Sorting algorithms. How efficient is each of them? What are some kinds of inputs that work best on each of them?
- (10) ways to represent a graph in memory (objects and pointers, matrix, and adjacency list) — familiarize yourself with each representation and its pros and cons.
- (2) Bloom filters: https://llimllib.github.io/bloomfilter-tutorial/
- (4) Implement a trie-tree
- (2) Implement a red/black tree in Python
- (4) Implement A* algorithm in Python
- (6) Binary Heaps
- Implementation in Python
- Big-o for insert, popMin, getMin
- Know that binary heaps aren't usually faster than BSTs, but are faster in practice and consume less memory (why?)
- (10) Dynamic Array (ArrayList). Implement and know how resizing works
- (8) Implement quick sort (reference)
- (6) What are some techniques to balance BSTs?
- (6) What are B-trees?
- (2) Read about treaps: https://en.wikipedia.org/wiki/Treap
- (4) LeetCode (931 Todo, 12 Solved, 2 Attempted)
To prepare for backend/systems questions:
- (8) Reader/writer locks
- (8) Files in linux, file descriptors
- (8) What's a socket?
- (1) What's anycast DNS?
- (8) Normalization in dbs: StackOverflow answer
- (10) DB indices: know that they speed up reads but slow down writes. They also take space and are implemented with B-trees
- (6) Mutexes/semaphores
- (4) Monitors: wikipedia:Monitors
- (6) Deadlocks and other concurrency problems: Quora answer
- (10) What's the heap of a program? The stack? SO answer
- (4) Malloc: how does it work? SO answer
- (4) How do system calls work in general? SO answer
- (10) Threads vs processes: SO answer
- (6) Database indices: how are they implemented?
- (8) Understand deadlock, livelock, and how to avoid them.
- (6) how context switching works, how it's initiated by the operating system, and underlying hardware
- (2) How does process scheduling work
- (4) Green threads: what are they? See Green vs Native threads and gthreads/intro.html
- (8) Use each one of the APIs described in https://docs.python.org/2/library/threading.html in a toy program to understand them better
- (8) Write a C program using epoll or kqueue
- (4) Know about nginx's main blocks/configuration
To prepare for design interviews:
- (10) Have an answer for NoSQL vs SQL
- (8) Design question primer: donnemartin/system-design-primer#system-design-interview-questions-with-solutions
- (10) distributed hash table system -- how to design one
- (10) How does consistent hashing work?
- (6) Read this Quora answer about design interviews
- (8) Watch How We've Scaled Dropbox
- (2) Read How To Ace A Systems Design Interview
- (2) Read Preparing for Your Software Engineering Interview at Facebook
- (2) Read Composing and Scaling Data Platform
- (5) Read The Log: What every software engineer should know about real-time data's unifying abstraction
- (10) Read a bit about Nginx's architecture (link)
Do not fit in the above categories (miscellaneous):
- (10) Go through the TripleByte interviewing process
- (10) SQL review (JOINs especially)
- (7) Fearless salary negotiations (Amazon link)
- Read fearless salary negotiation free sample
- Read fearless salary negotiation book
Finally, what I did not do (the items left on my giant TODO list basically). I will never know if these would have been useful to do or not...but here they are anyway:
- Complete this sysadmin focused quizz
- How to deal with nested state problems with Redux?
- Topological Sort: Arranges the nodes in a directed, acyclic graph in a special order based on incoming edges.
- Minimum Spanning Tree: Finds the cheapest set of edges needed to reach all nodes in a weighted graph. (greedy works! Pick edges based on their weight)
- Tail Call Optimization: how does it work in Scheme or JS? Why don't languages like Python or Java allow it?
- Read the system design questions portion of InterviewBit
- Review what Paxos is and how it works (Paxos Made Simple)
- Read this (about system design interviews)
- Read Please Stop Calling Databases CP or AP
- Read Learning About Distributed Systems
- Read Building a Scalable Webapp on AWS
- Given an N by N grid of positive integers which represent terrain heights, determine how many grid locations will have water flow over the continental divide (NxN diagonal, 1-1, 2-2, etc) when it rains, not including the divide itself.
- Know how red/black tree (wiki page) , splay trees or AVL trees are implemented
- Read https://akkadia.org/drepper/newni.pdf
- Read this paper about events
- Go through InterviewBit
- Do skiena's book's exercises
- Go through a few exercises in http://greenteapress.com/wp/semaphores/
- Review concepts listed at leonardomso/33-js-concepts
- Read this paper about memcache scaling
- Read Why Events Are A Bad Idea (for high-concurrency servers)
- Read Paxos Made Live - An Engineering Perspective
You made it. You're a hero. ♫ This is the end ♪.
To Ryan N. and Jon L.: thank you so much for the valuable feedback on early version of this article! You rock ❤