The numbers each represent the number of neighboring fields visited by the loop on a segment, where each '?' stands for a positive integer. If a field contains more than one number, each number corresponds to a segment and between two segments the loop must visit a different field.
Solution code in the example: 53
The puzzle (Penpa):
Solution code: In reading direction for each field with '?' the greatest value for one of the '?'.
on 5. September 2024, 22:10 by DiMono
git.io links are dead. This one works, with answer check: https://tinyurl.com/ye269n4e
on 17. January 2022, 16:00 by Mody
Hat Spaß gemacht :)
on 2. January 2022, 14:19 by zuzanina
Sehr schön!
on 31. December 2021, 03:02 by MariaL
That was really fun to solve!