Wow, the solution to this one is really fascinating. I felt like I was just stabbing in the dark trying to find it, and eventually just happened upon it. It feels like it makes some amount of sense in retrospect, but also feels very tricky to find. Neat idea.
Nice one! The solution here feels really logical, but at the same time there's a bunch of other reasonable-seeming ideas that optimize to 68, and it's a bit hard to filter those out and find the right one. Tricky to optimize, glad to have solved though!
Insights