Yajilin

[from Nikoli website]

Draw a single line with a loop following the next rules:

1. Lines must pass through the centers of cells horizontally or vertically and never cross, branch off, or go through the same cells twice.
2. Cells where the line is drawn must not be black.
   
3. Black cells must not touch each other horizontally or vertically.
   
4. Lines don't go through numbered cells. Numbered cells cannot be black cells.
5. Numbers represent how many black cells are at the direction of the arrow.

Solution: