advent-of-code-ocr VS adventofcode

In past years, I’ve created Advent of Code OCR for Python to convert ASCII letter art from these problems into plain text you can copy and paste.

Python: advent-of-code-ocr module by /u/bsoyka (original post)

The OCR is based on the number of active pixels for each column. The letter "E" has 6 lit pixels in the first column, 3 pixels in the 2nd and 3rd column and 2 pixels in the last column. By looking at the character list (thanks bsoyka on github!) I could craft a lookup table. The four integers will be shifted and added together to get a single integer. The 6,3,3,2 is transformed to 6<<0 + 3<<2 + 3<<4 + 2<<6 = 194 (the bits overlap, I know, but there are no collisions). The index of 194 in this magic list is 4. By adding 65 (ascii value of 'A') I can get the actual character with chr().

Part one went fairly fast, but spent quite some time on getting part two right. I settled on the approach of just iterating over the grid and using a boolean to see if I had to count elements or not. However, I had some issues figuring out when to swap, this post by /u/rogual helped me figure it out. After that I lost quite some time on an error that only occurred with my input, not with the example input. It turned out that my loop (which I take form my p1 solution) didn't include the start node, which caused all sorts of counting issues.

[Language: Elixir] https://github.com/mathsaey/adventofcode/blob/master/lib/2023/4.ex