I wanted to add that Shenzhen and TIS problems have much more constraints, which makes it challenging and forces you to think of dramatically different solution

I wanted to add that Shenzhen and TIS problems have much more constraints, which makes it challenging and forces you to think of dramatically different solutions (after discovering that I ran out of instruction or data space in each module). I have literally spent a week trying to figure out how to solve some of the more complicated Shenzhen problems (and then I noticed the dev released an update that simplified those problems).