peek at solution solve puzzle
quality: difficulty: solvability: deep lookahead
Puzzle Description Suppressed:Click below to view spoilers
#1: Wombat (wombatilim) on Mar 17, 2023 [HINT]
Initial LL completes 35%.#2: Web Paint-By-Number Robot (webpbn) on Mar 17, 2023
C1: EL marks R7-9 and R26 white. LL.
C39: EL v.R37-38 marks R14 black. LL.
Deep lookahead C39: If the 5 goes into R13, it marks R13 C2-37 white. This puts the 11 in C5 down into R24. The upper 1 in C6 would be placed in R23, and the 4 in C6 would extend into R9. This marks R9 C9-35 white. R10C32 needs to be part of a 5 clue, but now we don't have room to finish it. Therefore R13C39 must be white. LL.
C32: The black in R14 must join with either R10 or R18. If it goes to R10, then R6-9 C33 would be black, but this would put a black into R9C32 as well, so R15-17 C32 must be black instead. LL.
C6: The black in R10 is either a 1 or the start of the 4. If it is a 1, then everything open below it in C6 is marked white, and the 11 in C5 is pushed into R12. If it is the 4, it extends into R13. Either of these options places blacks in R12-13 in either C5 or C6, so in R12 we can mark C2-4 and C7-37 white, and in R13 we can mark C2-3 and C8-28 white. LL.
R15: IEL marks C26-30 white. LL.
C5: However you place the rest of the 4, it places a black into C4, which will finish that column. R1, R5, and R22-24 in C4 are white. LL.
C1: However you place the rest of the 4, it places a black into C2, which will finish that column. R1, R5, and R15-26 in C2 are white.
R6: There cannot be a 3 in C17-19 because R3 only has one more empty space than 1 clues, and placing a 3 here would mark 2 of the R3 spaces white. Therefore R3 C17-19 are white. LL.
C17&19: The 3s here either both go up or they both go down, since in R2 they would use a 3 clue that spans both columns. If they both go down, it would use up both 1s in R5, which would put C1, C5, C9, C13, C22, and C28 all into R2. This is too many, so the 3s in C17 and C19 must go into R2 instead. LL.
C13: The 4 will span either R2 or R6, either of which will place black in C14, completing that column. R19, R21, and R23 in C14 are white. The same logic can be used in C22 and C28 to mark the same rows white in C23 and C27.
LL to finish.
Found to have a unique solution by wombatilim.#3: Web Paint-By-Number Robot (webpbn) on Mar 17, 2023
Found to be solvable with deep lookahead by wombatilim.#4: Valerie Mates (valerie) on Mar 18, 2023 [SPOILER]
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