User blog comment:QuasarBooster/Bashicu matrix version 4 in Python!/@comment-35470197-20191109233117/@comment-24923514-20191110041232

Ooooh, I see the issue now! The second 1 is the parent of the rightmost 2 but then the parent of the second 1 is the 0, so the first 1 gets skipped. I'm really dumb for not noticing that earlier.