Nanro first appeared in a Nikoli publication.
Puzzle and Goal
An unsolved puzzle consists of a rectangular grid divided into regions. Some numbered clues have been provided.
The goal is to fill in numbers in each region.
The solved grid must satisfy the following conditions:
Each region must contain exactly one number value.
Each number N must appear N times in the region.
Each 2x2 area has at least one empty cell.
All numbers are orthogonally contiguous.
The same number can't appear on opposite sides of a region barrier in orthogonally neighboring cells.