peek at solution solve puzzle
quality: difficulty: solvability: deep lookahead
Puzzle Description:
(This puzzle was recovered from the 2016 database crash. Description not available.)
#1: Brian Bellis (mootpoint) on May 29, 2019 classify
Winky face#2: Joe (infrapinklizzard) on Oct 27, 2019 [HINT] classify
After LL#3: Web Paint-By-Number Robot (webpbn) on Oct 27, 2019 classify
Smile logic in rows 4&6 finishes the top
The picture and the symmetry of the remaining clues make it obvious what the bottom looks like, but logically it is hard to prove without deep lookahead.
Found to have a unique solution by infrapinklizzard.#4: Web Paint-By-Number Robot (webpbn) on Oct 27, 2019 classify
Found to be solvable with deep lookahead by infrapinklizzard.#5: Frank Camp (marakesh) on Jan 5, 2020 [HINT] classify
I did the bottom part as follows:#6: Joe (infrapinklizzard) on Jan 6, 2020 [HINT] classify
Prove that R13C3 and R13C13 cannot be black
LL
Prove that R9C7 and R9C9 cannot be black
Prove that R9C6 and R9C10 cannot be black
LL
I think this is moderate lookahead, right?
Frank, your first line is deep lookahead. You must place the 5 and then place the crossing 3s into r12, which then forces the crossing 2s into r14 which then could either
> go right into c8 which would trigger the 2 which would create a conflict in r13, OR
> go left into c5 which would then need two more steps to get to a conflict.
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