Skyscraper Sudoku

Skyscraper Sudoku contains clues around the edge. The task is to place digits in the grid. Each digit represents the height of the skyscraper in each cell. The numbers outside the grid represent the number of skyscrapers seen from the corresponding direction.

The formats of sudoku files:

• SKSD - Skyscraper Sudoku (9 x 9);
• SKSD6 - Skyscraper Sudoku (6 x 6);
• SKSD8 - Skyscraper Sudoku (8 x 8).