“Area connected to a given node in a multi-dimensional array with some matching attribute”

Anyone using old computers for graphics remembers the strangeness of “flood fill”: The 1950s and 1960s computers were so sluggish that their consoles with blinking lights were not just for show; the operations were slow enough that you could still follow the lights in real time. This ceased to be true soon afterwards. The microcomputer revolution temporarily reset some computing progress, but by the 1980s and 1990s more and more things were happening too fast for us to keep up. But here (this above is Paint in Windows 1.0, and you can try for yourself in a browser!) was one example where you could still see an algorithm working hard. It was mesmerizing and educational, and it was a rare example where perhaps you didn’t mind the computer taking its sweet time. Even messing up like I did above – maybe especially messing up – ended up fascinating to watch. Wikipedia has examples of a few different flood fill algorithms, which are even more interesting: A few years later, Minesweeper had…