PROBLEM 42.
A hot spring resort is arranged on an n×n board divided into n pools. Place capybaras subject to the following constraints:
- (i)exactly one capybara in every row and every column;
- (ii)exactly one capybara in every pool;
- (iii)every capybara sits adjacent to a hot spring;
- (iv)no capybara occupies a rock.
Each board is generated with exactly one solution and verified by machine. Forty-one boards are warm and reasonable. Board 42 is built by hand and is neither.
Solution: left as an exercise for the reader.
fig. 2 — the constant.
present on every board. responsible for nothing.
present on every board. responsible for nothing.
unsolved
fig. 1 — warm-up instance, 5×5, one solution. printable. the game begins here and stops being polite around 7×7.
legend: ♨ hot spring · hatched cell = rock · pencil = a previous reader
recorded attempts:
again?