(05-10-2018 09:55 PM)Valentin Albillo Wrote: no one posted any code or comments for this one either so I'll also save my original solution for a future article or something. As I said at the beginning of this post, it's a real pity as this Step was solvable (partially or in full) using most any HP calc model, and there are at least 3 ways to handle it, including brute force which will quickly become unfeasible as for 11-digit numbers there would be some 90 billion numbers to try, so more sophisticated techniques are required to reach that far in reasonable times (a few minutes).

By the way, I didn't ask for 12/10-digit solutions because for some 12/10-digit numbers the sum of their digits raised to the 12th/10th power exceeds the 12/10-digit range. Also, there are no 12-digit Selfies (but there's a unique 10-digit one).

I put 3 hours into this and one sleepless night (could not stop thinking how to optimize). It'll continue to haunt me just like SSMC #20's last problem continues to do today. Coincidently I was reading Henry Ibstedt yesterday.