Lazy River (w/ Nordy)
(Published on 8. February 2024, 18:27 by mathpesto)
A collaboration by Nordy and Math Pesto.
Rules:
Within the main 9x9 grid, normal sudoku rules apply.
Region Sum Loop: Draw a single closed loop that moves orthogonally through the centers of cells, and does not branch, overlap, or intersect itself. The loop can move in and out of the main 9x9 grid except for the black cells. The loop acts as a region sum line: Digits on the loop have the same sum in each region the loop passes through. If the loop passes through a region multiple times, each individual segment sums separately. (Each 3x3 box is a region, and the cells outside the main 9x9 grid comprise a single region.)
Outside Clues: Numbers in cells outside the main 9x9 grid equal the number of loop cells in the corresponding row/column of the main grid (loop cells outside the grid are not counted).
Sweepers: A digit in a circle equals the number of loop cells in the (up to) 8 surrounding cells, plus itself if applicable.
Kropki: A white dot joins two consecutive digits, and a black dot joins two digits in a 1:2 ratio. The loop must go directly through every dot.
Not all circles or dots are necessarily given.
Solution code: Within in the main 9x9 grid, the digits on the loop in Row 1 followed by the digits on the loop in Row 5 (left to right)
Comments
on 28. September 2024, 11:16 by Christounet
Awesome. Thanks :)
on 9. September 2024, 22:58 by StephenR
Some interesting logic, thanks.
on 16. February 2024, 10:46 by Piatato
Fun!
on 16. February 2024, 04:14 by moonear
very natural and fun
on 11. February 2024, 02:22 by madhupt
Stunning puzzle! Starts off beautifully, gets harder but remains smooth throughout. A very very satisfying solve. Thanks for setting and sharing this.
on 10. February 2024, 16:10 by Niverio
Very enjoyable! The way the loop builds is very smooth.
on 10. February 2024, 04:06 by wand
loved it - many surprising loop interactions
on 9. February 2024, 12:37 by Snookerfan
Excellent puzzle! Lots of fun, thank you
on 9. February 2024, 09:37 by Bankey
Brutal, absorbing, and super fun! Thanks, @ mathpesto and Nordy :). Definitely a 5* for me; hats off to those who found it less.
on 9. February 2024, 00:13 by Myxo
Awesome puzzle! I enjoyed that a lot.
on 8. February 2024, 23:00 by KNT
great puzzle! Almost fell for the trap near the end :)
on 8. February 2024, 22:26 by bansalsaab
Brilliant as always. R4C11 :-)
on 8. February 2024, 20:39 by yttrio
Phenomenal puzzle! Loved working out how the loop had to work through various types of logic (going through the 6x6 definitely helped).
on 8. February 2024, 20:22 by mathpesto
clarified rules
on 8. February 2024, 19:40 by samuel1997
Absolutely brilliant!
