The origin of this puzzle is not known.
Puzzle and Goal
An unsolved puzzle consists of a square grid divided into 1xN shaped regions, where N is a factor of the size of the grid.
Some of the cells contain number clues.
The goal is create fill in each region with the numbers 1 to N, according to the clues.
The solved grid must satisfy the following conditions:
Each number must appear with the same frequency in each rank (for instance, if the grid is of size 6 and the regions of size 3, then each number must appear twice in each rank).
Orthogonal neighbors cannot contain the same number.