Ripple Effect is NP-complete. We reduce from 3-SAT.
Tag Archives: np-complete
Puzzle 75: TomTom is NP-complete
This post has two puzzles!
Latin Square Put an integer between 1 and the length of the grid (5) inclusive such that each row/column has each number exactly once.
Expected difficulty Easy • Answer • Comment/E-mail if you want a solution to be published
Puzzle 75: TomTom is NP-complete
Latin Square
TomTom Put an integer between 1 and the length of the grid (10) inclusive such that each row/column has each number exactly once. The number at the top-left of each region indicates the value of a mathematical operation (addition, subtraction, multiplication, division) applied successively to all digits in the cage, starting with the largest digit for subtraction and division (e.g. 1,2,4 with subtraction is a 1- clue as 4-2-1 = 1). (Description from Grandmaster Puzzles)
Expected difficulty Easy • Answer • Comment/E-mail if you want a solution to be published
Puzzle 75: TomTom is NP-complete
TomTom
I guess the two puzzles above prove that TomTom is NP-complete. We can see a trivial polynomial transformation from a Latin Square to a TomTom, and Latin Square is NP-complete.
Chaos at the Sky 
