In general, it has great mechanical sympathy. You need to split your larger problem into smaller sub-problems, and then figure out which sub-problems depend on each other using the recursive formulation. Once you have done that, there should be no more need to have a stack, so you can just use an array to store the results of the depended on problems, and a loop to change which problem is being solved.
This article doesn't make the final step from recursion to loop but you would probably want to if you were doing DP in production.
Edit: Actually the article does make this jump. See the last code snippet before the conclusions section. Note also the second note after the snippet, which explains that the snippet itself uses a larger array than is necessary.
As for the second quote, the surrounding context explains that the validator will by default return an error if you point to a single object using two different pointers with different opinions on what the pointee's type is. This doesn't sound like a safety issue, since the validator is being too conservative rather than not conservative enough.
The first quote is probably in part referring to the second quote. If that is all it is referring to, than there is no safety issue. If there are other similar issues but rkyv chooses to reject valid archives rather than accept invalid ones, then there also is no safety issue. However, that isn't unambiguous, so I can't say for certain that it isn't possible to misuse the library from safe rust.
At least for the PATH, you can also automate the looking. When on a new POSIXy system, I usually try "(IFS=: ; ls $PATH)" at the shell to get a listing of all programs available.
This article doesn't make the final step from recursion to loop but you would probably want to if you were doing DP in production.
Edit: Actually the article does make this jump. See the last code snippet before the conclusions section. Note also the second note after the snippet, which explains that the snippet itself uses a larger array than is necessary.