I also took this opportunity to start learning how to use my Nikon D90. No more auto mode, only shutter, aperture or P mode from now on!

deliberate_practice_letter.pdf (53Kb)

These days I keep a printed copy with me at home and at work.

Feedback strongly welcome.

Algorithms

Articles

• Topcoder Algorithm Tutorials
• Algosort – repository of algorithms

Courses

• Jeff Erickson’s Algorithms Course Materials
• MIT OpenCourseWare’s Introduction to Algorithms

Problems

• CareerCup
• Facebook Puzzles
• UVA Online Judge
• ICPC
• Project Euler
• Sphere Online
• ZOJ Forum
• Topcoder
• Codechef
• Google CodeJam
• Facebook HackerCup (problems 2010)

Recommend Books

• Introduction to Algorithms
• From Baylor to Baylor

Techniques and classes of problems

(Taken from ZOJ Forum)

• Dynamic Programming
• Greedy algorithms
• String management
• Simulation problems
• Abstract Struct Problems
• Search Problems
• Number Theory Problems
• Geometry Problems
• Tree Struct Problems
• Graph Problems
• Matching Problems
• Combination Problems
• Shortest Path Problems
• Game Theory Problems
• Maximum Flow Problems

Software Engineering

Articles

• How to design a good API and why it matters
• StackOverflow’s community recommended books

Recommend Books

• Clean Code
• Code Complete
• Art of Computer Programming, Volumes 1-4A
• The Pragmatic Programmer

Software Engineering interviews

• Cracking the Coding Interview
• Programming Interviews Exposed: Secrets to Landing Your Next Job, 2nd Edition (Programmer to Programmer)
• How to rock an algorithms interview

Algorithm to solve any algorithmic problem

1. Understand the problem statement
2. Run through an example
3. Come up with the easiest solution
4. Explain the solution
5. Prove that it works
6. Is it the fastest that you can do? If not go to 3.
7. Watch-out for special cases

Random problems

Few divide-and-conquer problems:
- nearest pair of points (2D) in O(nlogn)
- counting inversions in an array
- array shuffling
input : a1,….an,b1,…bn
output: a1,b1,….an,bn

A few dynamic programming problems by name:
- Max contiguous sum in array
- Max subset sum of non-adjacent elements in array
- longest increasing subsequence
- longest common subsequence
- shortest common supersequence
- longest oscillating subsequence (google interview question)
- longest accelerating subsequence
- longest Arithmetic Progression subsequence for unsorted array (google interview question)
- Matrix chain multiplication
- maximum value of expression consisting + and *
- minimum number of palindromic substring
- cutting stick (ACM UVA problem)
- 0/1 Knapsack
- counting ways of making a change
- Min. number of coins for a change
- 2-partitioning a set with/without repeations of items minimum sum difference
- Edit distance
- convert string to palindrome with minimum deletions /insertions
- Max. rectangle sum
- Max rectangle/square submatrix of 0 and 1

Do you know any other good algorithms resource? Leave it in the comments!

Black sand which is so typical from Lanzarote. We took that little trail to go to the beach and in search of dinner.

The next day we decided to investigate the area by bike. Between more touristy areas you could see lovely
corners with almost no one on sight.

Yellow pedal based vehicles packed to the roofs with bright red skinned British and Germans. Little kids would use the horn whenever we passed by them and a second later the whole shrimp family would giggle all at once.

Even though there were irish restaurants and pubs on every shopping center we were able to enjoy more traditional Spanish dishes.

Our apartment was advertised as being operated by a company but we soon discovered that the real owners were the cats. They were everywhere, they would enter through open doors and windows, jump into hanging towels with their claws, meow to death or wrestle in front of us before breakfast.

Lanzarote is a volcanic island of 80km long by 25km wide and, at one point in the last 200 years or so, one fourth of its surface was covered with magma from the last big eruption in the island. During our visit to Timanfaya Park, shown above, we could confirm first hand the out-of-this-world feeling of the resulting landscape.

Friendly camels resting between one group of tourists and the following at the Timanfaya Park.

El Golfo was originally a full blown crater but time has taken its toll and has transformed it into the beach that you can see above. The atypical water color is due to the amount of minerals in the crater crust.

Loes trying to get me drunk and me trying to find a difference between that wine and vinegar.

A few days later we visited a cactus paradise with 900 different kinds of cactus.

People from Lanzarote use volcanic rock and black sand everywhere, the cactus paradise was no exception.

Later that day we visited Jameos del Agua. It takes its name from an underground cavern that we were told was really impressive. Regrettably we didn’t find it as astonishing as for example this swimming pool a few steps away from the cave.

After Jameos del Agua we travelled north and reached a really nice viewpoint from where you could see nearby islands like Fuerteventura or La Graciosa.

We finished our trip by a visiting Cesar Manrique’s house. The house has rooms above and below ground. The underground rooms were carved out by lava and Cesar made rooms out of them like this one and the one in the next photo.

After several months in Dublin with its lack of sunlight it was a very nice change that reminded us of the energy that full days of sun have.

This adventure starts about an hour before taking the previous photo. I had decided I wanted to go visit the Golden Gate that day because I already had tickets for Alcatraz for the day after which was my last day in San Francisco. The grey tint on buildings and cars, the white sky, the steep road ahead of me… The hints were everywhere but I wasn’t looking at them.

I went to a bike shop I had carefully researched the night before, I rented a bike and started my journey with my trusty Google water bottle, one banana and some Mexican version of chips. Several minutes later the sky started to clear up while I cycled by the seaside and my optimism regarding the weather was leaving a long trail behind me.

The second hint came five minutes later. Looking back it was evident that I should have stopped and returned at that point but I come from a country where we have two important genes. One of them makes you feel like you are a “macho ibérico” and the other one is an Iberic relative of Biff Tanen from Back to the Future who sits on our shoulders and says “¿A que no hay huevos?”.

I looked back one last time.

I then looked at my mount which was impatiently waiting for me and I quickly resolved to continue pedaling.

Several minutes later here, more wet than minutes before and at a distance from the Golden Gate where you still didn’t feel like an ant I saw this.

Before crossing the gate. Depiction of an optimistic who doesn’t check the weather before leaving home. The map in the front part of the bike was necessary. It took more than 30min of pedaling to get there from where I picked the bike and it wasn’t a straight line.

When you play too many videogames the real world starts to remind you of multitude of virtual worlds, like Half-Life 2 and Minecraft in this particular case.

After the cold and deadly bottom part of the bridge this is next point where you feel the tiniest.

There were phone cabins like this one every other pillar.

At the end of bridge the third hint was awaiting me. I was still fully optimistic believing that the weather would get better at Sausalito, my next stop so I dismissed it.

But the weather didn’t get better. It got worse. When I arrived to what I thought was the center of Sausalito everything but the Mexican equivalent of a 7 Eleven was closed. And a banana and a bag of chips aren’t enough fuel to pedal kilometers of steep road. I entered into the shop, I bought a funny looking sandwich and I made the Mexican cooks there realize that not every Spaniard is mad, or even knowledgeable, about soccer. After I recovered some energy I left the Mexican delicatessen in search of Muir Woods, a forest north of Sausalito with some of the tallest trees in the world. On my way there I passed through the real center of Sausalito where real restaurants, including Italian restaurants, were open and whispering my name. My optimism took a hit and I felt cheated by Sausalito. I was cold, I was tired, I didn’t have a single ray of sun tapping me on my shoulder and it was raining more and more but I still had some pride so I continued pedaling towards Muir Woods.

A few minutes later, almost outside of Sausalito the weather had became more and more intense. With utter despair I entered the last shop in town in search of an umbrella but they had none. By that time my third eye was completely open, drenched in water I accepted my defeat and turned back. My imaginary opponent, however, didn’t leave without scars as I made it to the next ferry that connected Sausalito to San Francisco as they were leaving covering in 4min and a few seconds a distance that, according to the map, required 10min. While looking back I silently shouted: “I’ll be back”.

I have come a long way since the days where I had 300 emails in my inbox with some of them waiting for months before being replied. However several weeks ago I again felt that I was spending too much time on email. Seeing unreplied emails accumulating for days at a time didn’t help getting rid of that feeling.

Why is it bad?

• Opening my inbox and seeing all those email sitting there and looking at me is frustrating and makes me feel guilty.
• It’s also time wasting because less than 1 out of every 20 emails I receive are so contrived or life changing that I need to read them multiple times.
• A consequence of being a time wasting activity is that I lose time that I could spend in other activities that I enjoy more like continuing my Division by Zero webcomic.

Solution?

Use at most 4 sentences in all my emails, no exceptions no matter what topic or recipient. If I need to communicate more information I use a different medium like a Google Docs document or a blog post and I add a link to it in the email.

Benefits?

• I spend less time in my inbox.
• My recipient spends less time reading my emails and frees her to do more interesting things.
• With 4 sentences I need to get to the point and I can’t conceal my “agenda”. That reduces one of the biggest problem with communication: misunderstandings.
• It makes me think hard about what I say and the way I say it. I can’t spend the same effort with emails that are paragraphs or pages long.

Shortcomings?

• Your emails will sound less personal than before because you send out less information.
• If you use email to communicate with friends that you don’t communicate with through other medium you are not going to be able to keep them as informed about you as before.

Alternatives?

Spending the same or more time on email wasn’t an option so the only other options were:

• Using less than 4 sentences: not feasible for me. I usually spend one full sentence saying “Bye” or “See you” and generally another sentence with “Hello,” or similar. In practice, I have about 2 or 3 sentences, instead of 4.
• Stop responding to some emails. Gladly I’m far from receiving so many emails that I have to do something that harsh.

Things to keep in mind

After several weeks using this approach I found out the following:

• I still feel like I sound personal which was one of my biggest concerns.
• This works for any other messaging system like Facebook and LinkedIn.
• I have to be careful not to start replacing periods with commas.
• 4 sentences is the limit, not the goal. If you can use less sentences do it.

At the beginning I added http://four.sentenc.es/ to my email signature to let people know why my emails were now more succinct. If 4 sentences is not the right number for you there are 5, 3 and 2 sentences versions available.

Do you have email under control? Do you use any other technique?

Two weeks ago we went to Bray and, from there, we took an approximately 5km long hiking trail along the coast towards Greystones. The Irish coastline reminds me of The Shire, the birthplace of hobbits in The Lord Of The Rings: completely green, with a minimum number of people and almost everybody smiles.

The beach is not the best place to take the sun or generally lie but you can see the good-natured intentions.

Neither this nor the next photo were taken by me.

Taking a break to recover energies.

Although my companion couldn’t hear them I was fully aware of the roars coming from the depths of that tunnel.

This is how the next one will look like.

Humans are curious creatures.

What is the sound of one hand clapping in the desert?

Special thanks to Reinoud for asking me about the comic for weeks and pushing me to complete it and to Killerpijos for beta testing the original version and giving valuable feedback.