Common Sudoku Patterns & Solving Techniques: From Basics to Advanced

Basic Patterns

• Single Candidate / Naked Single: Only one possible digit for a cell.
• Hidden Single: A digit can go in only one cell in a row, column, or box.
• Naked Pair/Triple/Quad: 2/3/4 cells in a unit share the same 2/3/4 candidates – eliminate those digits elsewhere in the unit.
• Hidden Pair/Triple/Quad: 2/3/4 digits appear only in 2/3/4 cells of a unit – other candidates in those cells can be removed.

Intermediate/Advanced Patterns

• X-Wing / Swordfish / Jellyfish: Same 2 candidates in 2/3/4 rows & columns – eliminate from other cells in those columns/rows.
• Unique Rectangle: Two pairs of cells forming a rectangle with same two candidates – avoids multiple solutions.
• Y-Wing / XY-Wing: Three cells with three candidates chain to eliminate a candidate elsewhere.
• W-Wing: Two pairs sharing two candidates, each with a third unique candidate – eliminate a shared candidate.
• Forcing Chains: Logical chains where a choice in one cell forces choices in others.

Strategic Habits

• Scan for low-candidate cells first.
• Use pencil marks (candidate lists).
• Work backwards from constrained areas.

Experience builds pattern recognition – keep solving!