It's that time of year again. Yep, you got it. Time for Advent of Code. I'm not feeling nearly as motivated as in past years but so far so good. Finished the first three days.

Today I got a good reminder - work through your examples. You can find today's problem here.

For part 1 you got a list of binary numbers and had to figure out how many ones and zeros there were in any given digit.

For example, if we had these numbers:

0010
0111 
1001
1010
1111

The ones digit has 3 total ones and 2 zeros. The 2s digit has 4 ones and 1 zero. You then had to do some calculations based on if there were more ones in a given column or more zeros.

Pretty straight forward. As usual, I'm working in Clojure so I used map and reduce to figure out the number of ones in each column and then did the required calculation. If you want to see the code, you can find it here. Later in the day I looked at other people's solutions and it was interesting in that a lot of people approached it differently - they basically looked at the list of numbers and rotated it so that columns became rows and rows became columns which then make counting ones and zeros easier, but I digress.

I then had to rush through part 2 because I had to leave for the ophthalmologist. I didn't know if my eyes were going to be dilated and if they were, I wasn't going to be able to come back to the problem until late in the evening.

I got something done but unfortunately, didn't quite finish. Fortunately, my eyes weren't dilated so after getting home I set to finish the problem.

Part 2 involved taking your list of numbers, calculating some values using the part 1 code and then using those values to eliminate some of the numbers. You then repeated this process until you were left with a single number. See the problem statement and if you want my solution for details.

I got something working but my answer was incorrect. I spent, well, frankly, too much time trying to figure out why. I was stumped. Finally I went back to the example in the question and actually worked through it (as opposed to glancing over it). I quickly saw my error. I had calculated the part 1 values based on the original data then kept applying those to the data list until it reduced to a single number. I was supposed to recalculate the part 1 values on the reduced data set each time instead. Once I realized this, it was a pretty quick solution.

This isn't the first time my carelessness cost me time. Back in 2016 I spent way too long trying to fix an Advent of Code problem where the problem was that I had the wrong parameters in a function (link).

In this case, the moral of the story is work through the provided examples!!!!

So, that's it for today. If you haven't checked out Advent of Code, I highly recommend it and if you want to see my solutions, however far I get, you can find them here.

Finally, in the spirit of the season, Natan composed a new Chanukah song.

If you're so inclined, you can check it out below: