Draw a single loop that passes orthogonally through centers of all cells. The loop cannot intersect itself or enter the same cell more than once.
Some regions are drawn and include a set of numbers in the upper-left corner. Each maximally straight segment in the loop (that is, a section of the loop between two consecutive turns of the loop) that is partially or fully contained in a region must have its length equal to one of those numbers. Every number in a region’s set must be represented by at least one maximally straight segment in the loop that is partially or fully contained in that region.
Notes:Variants:
- A '?' symbol represents a number whose value is for you to determine; however, it cannot represent a number that is already in the set of that region's numbers (either a given number or another '?').