Build A Maze/en
Aus Puzzlewiki
Instructions
Place some walls in the grid, creating a path going from one grey cell to another and visiting every cell exactly once. Walls are horizontal or vertical lines going along grid lines with their ends at grid nodes. Digits outside the grid show the lengths of all wall segments in corresponding direction. There should be at least one empty space between two segments.
History
Invented by Riad Khanmagomedov (Russia).