Cross the Tapa by Chris Green
or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode, a number entry mode for placing Tapa clues, and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)
Theme: Sequences
Author/Opus: This is the 10th puzzle from guest contributor Chris Green.
Rules: (Style created by Chris Green as a combination of Cross the Streams and Tapa rules.)
Shade some empty cells black to create a single group of black cells that are all connected to each other through their edges. No 2×2 cell area within the grid contains all black cells.
Numbers and symbols to the left/top of the grid represent all unshaded cells in the grid in that row/column in order, either from left to right or from top to bottom. The numbers and symbols represent the value of Tapa-style clues inside the grid, specifically the length of consecutive shaded blocks in the neighboring cells. If there is more than one number in a cell, then there must be at least one white (unshaded) cell between shaded groups.
The three symbols indicate different kinds of missing information.
– A question mark (?) represents a single missing positive integer as part of a clue (either alone or in combination with other numbers/question marks).
– An octothorpe (#) represents a single white clue cell which may have any combination of values including a single number or multiple numbers.
– An asterisk (*) represents an unknown number of white clue cells, including one, multiple, or no clue cells at all. Any clue cells indicated by an asterisk can have any combination of values including a single number or multiple numbers.
Also see this example by Thomas Snyder:
Answer String: Enter the length in cells of each of the black segments from top to bottom for the marked columns, going in order from A to B to C to D and separating each entry with a comma.
Time Standards (highlight to view): Grandmaster = 10:00, Master = 24:00, Expert = 48:00.
Solution: PDF
Note: Follow this link for other Cross the Streams and this link for other Tapa.
Tough!!! Nice puzzle, including some rather clever logic with the sequences.
I really liked the concept, but I struggled to find a logical approach beyond the first few entries. I had to make a guess, and then it flowed OK from there. I liked the example very much.
This is one of our harder posts even for a Saturday, probably because the rules are a little unfamiliar. The earlier Cross the Tapa from 18 months ago (https://www.gmpuzzles.com/images/puzzles/2017W25-Mystery.pdf) might be helpful background?
On this specific puzzle, here are a few tips in ROT-13 form. (Any other solvers are welcome to add their own comments.)
Gur znva fgnegvat uvag V jvyy tvir lbh vf gb ybbx ernyyl uneq ng ebj 9 naq nyfb jurer vg vagrefrpgf ? be ?? pyhrf va gur pbyhzaf. Nyy bs 7 6 5 4 zhfg or ? pyhrf, abg ?? pyhrf, fb lbh pna fgneg gb qb qrqhpgvbaf yvxr guvf:
E910 pnaabg or hafunqrq naq = 4 (ab jnl gb trg gjb ?? pyhrf orybj gung pryy gb nyybj sbe n ? = 4).
E9P8 pnaabg or hafunqrq (juvpu jbhyq erdhver ? = 4 be 5). Vs E9P8 vf n ?, guvf sbeprf E10P8 gb or n ?? gb borl gur pbyhza pyhr. Vs E9P8 vf n 4 gung vf abg n cbffvoyr cnvevat bs Gncn pyhrf. Vs vg vf n 5, gura E9P9 zhfg or 4 naq gung nyfb vf abg inyvq.
Hygvzngryl, lbh fubhyq svaq gurer ner whfg 6 cbffvoyr pryyf va ebj 9 sebz P2 gb P7 jurer gur 7 6 5 4 pyhrf pna svg jvgu gjb nqqvgvbany funqrq pryyf gb cynpr.
N qvssrerag guvat gb abgr nobhg Pebff gur Gncn nf gung va nal ebjf be pbyhzaf jvgubhg nfgrevfxf lbh nyernql xabj ubj znal birenyy pryyf jvyy or funqrq. Ebjf 2, 4, 7, 9 unir rknpgyl 6 funqrq pryyf rnpu. P5 jvyy unir 8 funqrq pryyf. P6 jvyy unir 5 funqrq pryyf….
Interesting. My breakin was rather different actually:
Jurer gurer vf n 3 naq n 4 va frdhrapr (E2 naq E7), gur fdhner arkg gb gur guerr pnaabg or funqrq – vs vg jnf, gur pryy gb gur evtug bs gur guerr pnaabg or funqrq fb zhfg pbagnva n 4, ohg gura gurer vf ab jnl bs znxvat gur 4. Guvf vzzrqvngryl cynprf n 3 va E7P1, ohg vg unf shegure vzcyvpngvbaf ba E2. Vs gur 1 vf abg cynprq va P1, gur pryy gb gur yrsg bs gur 1 zhfg or funqrq, fb nyy bgure pryyf nebhaq gur 1 pnaabg or funqrq. Gung zrnaf gur 2 vf gb gur vzzrqvngr evtug bs gur 1, naq gb pbzcyrgr gur 2 gur pryy gb gur evtug bs gur 2 zhfg or funqrq, zrnavat gurer zhfg or n funqrq pryy orsber gur 3. Gurersber, gur 1 zhfg or va E2P1. Abj, vs gur pryy gb gur evtug bs gur 1 vf funqrq, gur svefg guerr ahzoref va P1 zhfg or guerr 1’f, zrnavat gur pryy qverpgyl orarngu gur guveq 1 pnaabg or funqrq, fb zhfg pbagnva n 5, ohg guvf pbagenqvpgf gur gjb ahzore pyhr tvira va P1. Gurersber, gur pryy gb gur evtug bs gur 1 vf gur 2, naq fb gur 3 naq 4 zhfg pbzr arkg, juvpu zrnaf gur erznvavat pryyf va gur ebj zhfg or funqrq.
A very pretty puzzle. Solve was tough but fair; went purely logically for me, but there were a few times when I had to stop and stare at the grid for a while before I found the next deduction.
It would be nice to see more puzzles of this type. Also, I wonder if Cross the Streams couldn’t be combined with other types in a similar way.