3. Sudoku puzzles are popular number-based puzzles. A game consists of a 9 x 9 grid made up of nine 3 x 3 blocks. Each row and each column of the game must contain exactly one of the 9 digits 1 - 9;...

DISCRETE MATH. Please help me with this one? Thank you!

Extracted text: 3. Sudoku puzzles are popular number-based puzzles. A game consists of a 9 x 9 grid made up of nine 3 x 3 blocks. Each row and each column of the game must contain exactly one of the 9 digits 1 - 9; furthermore, each 3 x 3 block must contain exactly one of the digits 1 through 9. Following is a sample puzzle, used by permission from Web Sudoku at http://www.websudoku.com, where you can generate puzzles at any of four levels of difficulty. Try completing this puzzle. 2 1 7 4 3 2 1 4 5 8 9. 5 8 7 1 8 6 3 | 9 5 8 2 3 7 1 3 4 5 8 7 2 4.