The programming puzzle that landed me my job

Back in 2011, as I was getting a bored with my job and I started looking for a new job. During my search, my friend Daniele (with whom I had built Novlet and Bitlet years before) forwarded me a link to the careers page of the company he was working for at the time, ITA Software.

While Google was in the process of acquiring ITA Software, ITA still had a number of open positions they were looking to hire for. Unlike Google, however, they required candidates to solve a programming challenge before applying to engineering roles.

The problems to solve were surprisingly varied, ranging from purely algorithmic challenges to more broadly scoped problems that still required some deep technical insight. As I browsed through the options, I ended up settling on a problem that intrigued me because I thought it resembled a problem I might one day wanted to solve in the real world and seemed to try to test both the breadth of my knowledge (it required good full stack skills) as well as my understanding of deep technical details.

I have good memories of the time I spent investigating this problem and coming up with a solution. When I was done, I had learned about a new class of data structures (suffix trees), gained a deeper understanding of Java’s internals. A year later, I got a job offer due in part to this puzzle.

What to look for when hiring

A while ago, I found myself in the enviable position of having to rapidly grow my team. By then, I had done a large number of technical interviews, so I had an idea of what to look for in strong candidates for Software Engineering positions. However, I felt like I lacked a framework for understanding how likely a given candidate was to succeed if they had joined my team, beyond a very loose definition of “culture fit”.

As I was trying to better understand what I was looking for, I started to think about what I value in the people I work with and to reflect on traits I found to be quite common among some of the most successful people I have worked with over the course of my career.

While I would not expect every person I work with to exhibit all the qualities I list here, I am always positively impressed when I come across someone who exhibits more than a few and equally concerned when I see no hint of any of these characteristics.

Over time, I became quite sensitive to some hints that suggest someone could possess one of the these traits and I learned to probe further whenever I see them.

Here a list of the most important characteristics I learned to value in anyone I work with, regardless of job function.

Visual and HTML Testing for Static Sites

Over a year ago I switched from having my site hosted on a CMS to having it built statically and served as a collection of static pages. I have been extremely happy with the end result for all these months – the site is very easy to update and effortless to maintain – but I just made a few changes that made my experience even better.

Zing LED Smart Night Light

I liked these WiFi enabled, motion-sensing night lights so far, I only wish they had 3 more features.

Migrating From Wordpress to Hugo

After many years of running my site on Wordpress, I just migrated this site to Hugo. The migration was quite simple, this post outlines the main steps and offers a few helpful resources.

What’s wrong with Milan’s Open Data initiative

I spent some time during the last weeks playing with the Open Data published by the City of Milan. I did not have a clear goal in mind, except for building some interesting visualization of the Public Transport coverage of the city grounds.

A quick exploration of the dataset seemed to be encouraging: while most of the data was relatively useless, some datasets were indeed promising and worth spending some time. While at the end of the week I was able to get the result I had in mind (the heatmap below), I was left with that lingering feeling of dissatisfaction that accompanies me when I see good initiatives that can be dramatically improved by changing a few specific features.

Appsterdam Guru Session: Google App Engine for beginners

One of the things I was not expecting when I moved to Amsterdam was its active and vibrant tech community. Appsterdam, a non-profit organization focused around aggregating people with a passion for technology, is probably one of the central forces in this movement.

In my year in Amsterdam I had been to a few meetups organized by people from Appsterdam and always came back home having learned something new. This is why when my colleague Matt (who himself is quite an active Appsterdam member) talked me into presenting a guru session on Google App Engine, I saw that as an opportunity to return the favor.

Presenting Professional Invaders

A few weeks ago I attended The Next Web Conference in Amsterdam and joined a bunch of fellow programmers for another edition of the Kings of Code Hack Battle, the same kind of event as the one where Bring Your Own Music was born.

Following the usual schedule, after a brief presentation from the API partners (Spotify, SendGrid, Braintree, Deezer, Pearson, Nokia, Rebtel,, Smart TV Alliance and LinkedIn), all the attendees started evaluating ideas about what to build.

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Hacking @ The Next Web #TNW

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I teamed up with Alexander, a friend of mine I already had the chance to work with back in the days when I when I was consulting.

Having LinkedIn among the sponsors seemed to encourage us to build serious applications for serious professionals, but after discarding a few alternatives that would have been better projects for a Startup Weekend than a hackathon, we decided to take the opposite direction: building the silliest possible thing with the APIs we had access to.

What Van Gogh can teach us about persistence

I visited the Van Gogh museum in Amsterdam recently and, to my surprise, I left the exposition having learned something that matters beyond art.

Prettier source code on

Formatted source code

Posting source code on is quite simple: the platform already provides an extremely easy to use shortcode called sourcecode, based on a fairly flexible syntax highlighter plugin. By looking at the examples in the documentation page, however, it is evident that the default styling used to render sources is quite old-fashioned and does not fit most modern themes.

While the shortcode offers options to allow users to control many options of the rendering, it does not allow us to configure colors, fonts and size (the default size is so tiny that it is barely readable on high-resolution screens).

When I was writing the previous technical post, I did some investigations to figure out what options are available to post more readable sources if your blog is hosted on and I found out there are basically two alternatives.