alt Hacker NewsWell, it does make the solutions less impressive, right? Because it's much easier to compute the inverse of an integral than an integral. What's impressive here is more in composing problems that have nice answers and can't be solved by computer algebra systems, then the sock puppet trick to conceal that you ha the answer all along.
Reshetnikov didn't confess to them being reverse engineered, though. He confessed to them being conjecture arrived at after working on the problem for a bit by tweaking similar integrals in symbolic math software / numerical approximations. Every post was a gamble because it could have been wrong.
Of course, that could be a lie, but he came clean about other things that make sense retrospectively.