A simple code what generate a sudoku puzzle with solution.

/** SUDOKU GENERATOR

• Simple sudoku class generator.
• You can set to 9 level difficulty.
• You can display the solution.
• Copyright Bartosz Karallus 2015.
• Contact info@eltitobarte.com.
• ========================================================
• Instructions:
• include the file sudoku.php on your PHP code,
• create variable and declare the class ( $sudoku = new sudoku( $level ); ),
• type in $level variable the level that you want to use, if you leave empty the
• default level will be 0.
• then generate the puzzle using ( $sudoku->generate(); ).
• if you want to show solution include ( $sudoku->solution(); )
• that's all. Thanks.
• ======================================================== */