# 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 EasyAnswerComment/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 EasyAnswerComment/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.