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Aqre (Loop) (1242)
Instruction:
Shade some empty cells black. All black cells connect along edges to create a single connected region. (It is permissible for the region to touch itself at a corner, but touching at a corner does not connect the region.) No 1×4 or 4×1 group of squares can be entirely shaded black. No 1×4 or 4×1 group of squares can be completely unshaded. The grid is divided into regions by thick borders; a number in a region indicates exactly how many cells in that region must be shaded black. (The location of the number in the region has no significance.)
Additionally, it must be possible to draw a single non-intersecting loop through the centers of all shaded cells (and no unshaded cells), using only orthogonal loop segments.