Mastering Sudoku requires understanding and applying various solving techniques systematically. This comprehensive guide covers the most effective strategies from basic to advanced levels.
Basic Techniques
1. Single Candidate (Naked Single)
When a cell has only one possible number, fill it immediately. This is the most fundamental technique.
2. Single Position (Hidden Single)
When a number can only go in one cell within a row, column, or box, place it there.
Intermediate Techniques
3. Candidate Elimination
Use the rules of Sudoku to eliminate impossible candidates from cells.
4. Pairs and Triples
When two or three cells in a unit contain the same two or three candidates, eliminate those candidates from other cells in the unit.
Advanced Techniques
5. X-Wing
When a digit appears in exactly two cells in two rows, and those cells are in the same columns, eliminate that digit from other cells in those columns.
6. Swordfish
An extension of X-Wing involving three rows and three columns.