Complete Sudoku Techniques Guide: From Beginner to Advanced
Welcome to the Sudoku Techniques Learning Center! This page organizes all Sudoku solving techniques from beginner to advanced, helping you systematically learn and improve your Sudoku skills. Whether you're just getting started or looking to tackle harder puzzles, you'll find suitable learning content here.
We recommend learning in order - master basic terminology and beginner techniques first, then gradually progress to intermediate and advanced strategies. Each technique includes detailed explanations and diagrams to help you understand and apply them better.
Basic Knowledge
Before learning solving techniques, you need to understand basic Sudoku terminology and concepts.
Row, Column, and Box Naming Conventions Basic
Learn how rows, columns, and boxes are numbered in Sudoku - this is the foundation for understanding all techniques. This site uses numbers 1-9 for rows (top to bottom), letters A-I for columns (left to right), and boxes are numbered 1-9 from left to right, top to bottom.
Sudoku Glossary Basic
Quick reference for common Sudoku terminology including cells, candidates, bi-value cells, chains, strong links, weak links, and locked sets.
Beginner Techniques
These are the most basic solving methods, suitable for Sudoku beginners. Master these techniques and you'll be able to solve most easy and medium difficulty puzzles.
Naked Single Beginner
When a cell has only one candidate number remaining, that number is the answer. This is the most direct solving method.
Hidden Single Beginner
In a row, column, or box, if a number can only appear in one position, that position is the answer for that number. Determine the unique answer through row, column, and box elimination analysis.
Intermediate Techniques
After mastering beginner techniques, learn these intermediate strategies to solve more complex puzzles.
Naked Pairs Intermediate
When two cells in the same row, column, or box have exactly the same two candidates, you can eliminate these two numbers from other cells in that unit.
Naked Triples Intermediate
An extension of Naked Pairs, applicable to three cells and three numbers.
Hidden Pairs Intermediate
When two candidates in a row, column, or box appear only in the same two cells, those two cells must contain these two numbers, allowing you to eliminate other candidates from those cells.
Hidden Triples Intermediate
When three candidates appear only in the same three cells within a row, column, or box, those cells must contain these three numbers, allowing elimination of other candidates from those cells. Advanced version of Hidden Pairs.
Box-Line Reduction (Pointing & Claiming) Intermediate
Uses the intersection relationship between boxes and rows/columns to eliminate candidates. Includes Pointing (box candidates point to a row/column) and Claiming (row/column occupies positions in a box).
Advanced Techniques
These are advanced strategies needed for solving hard and expert-level Sudoku puzzles.
X-Wing Advanced
When a candidate appears only in the same two columns in two rows, that candidate can be eliminated from other cells in those two columns. Row-based X-Wing eliminates columns, column-based X-Wing eliminates rows. Classic advanced Sudoku technique.
Swordfish Advanced
When a candidate appears in at most three columns across three rows, that candidate can be eliminated from other cells in those three columns. 3×3 extension of X-Wing, expert-level Sudoku technique.
Jellyfish Advanced
When a candidate appears in at most four columns across four rows, that candidate can be eliminated from other cells in those four columns. 4×4 extension of X-Wing and Swordfish, the largest commonly used pattern in the Fish family.
Skyscraper Advanced
When a candidate forms a strong link in two rows (or columns) and they connect through the same column (or row), cells that can see both dangling endpoints can eliminate that candidate. An advanced elimination technique based on strong links.
Single Digit Chains (Skyscraper, 2-String Kite, Turbot Fish) Advanced
Three single-digit chain techniques based on strong and weak links: Skyscraper (two parallel strong links), 2-String Kite (row and column links via box), Turbot Fish (box link with row/column link). Master the core principle to apply all three.
Grouped Single Digit Chains (Grouped Skyscraper, Grouped 2-String Kite, Grouped Turbot Fish) Advanced
Extended versions of Single Digit Chains: when strong link endpoints extend to multi-cell groups within a box, use grouped strong links for candidate elimination. Includes Grouped Skyscraper, Grouped 2-String Kite, and Grouped Turbot Fish.
Grouped Skyscraper Advanced
When strong link endpoints extend to groups consisting of multiple cells within the same box, use grouped strong links for candidate elimination. The grouped extension of the Skyscraper technique that can discover more elimination opportunities.
Chute Remote Pairs Advanced
When two cells in a tower of three boxes have the same pair and the third box's Chute (3 cells in a row/column) lacks one candidate, we can deduce that one pair cell must be the other candidate, enabling eliminations.
XY-Wing Advanced
When pivot {X,Y} can see wing {X,Z} and wing {Y,Z}, Z must be in one of the wings, so cells that see both wings can eliminate candidate Z. Uses the special relationship between three bi-value cells for elimination.
XYZ-Wing Advanced
An extension of XY-Wing. When a triple-candidate pivot {X,Y,Z} can see wing {X,Z} and wing {Y,Z}, Z must be in the pivot or one of the wings. Cells that see the pivot and both wings can eliminate candidate Z.
WXYZ-Wing Advanced
A further extension of XYZ-Wing. When four cells contain exactly four different candidates {W,X,Y,Z} and form a chain relationship, Z must be in one of these four cells. Cells that can see all four cells can eliminate candidate Z.
XY-Chain Advanced
Eliminate candidates through chain structures formed by multiple bi-value cells. When the unshared candidates at chain head and tail are the same, cells that see both endpoints can eliminate that candidate. An extension of XY-Wing that supports chains of any length.
Multi Strong Links (3/4/5 Strong Links) Advanced
Connect multiple strong links to form an alternating chain, using the common visible area of the chain endpoints to eliminate candidates. Includes 3 Strong Links, 4 Strong Links, and 5 Strong Links patterns.
X-Cycle Advanced
Form a closed loop through alternating strong and weak links, using the cyclic relationship of a single candidate to make eliminations. When cells can see both endpoints of a weak link in the closed loop, they can eliminate that candidate.
BUG (Bivalue Universal Grave) Advanced
When the grid is nearly all bivalue cells (cells with exactly 2 candidates), the only trivalue cell must contain a specific digit to avoid multiple solutions. Uses the unique solution principle to determine the answer.
Unique Rectangle Advanced
Uses the unique solution principle to eliminate candidates by identifying rectangular patterns that would create a "deadly pattern" (multiple solutions). Includes Type 1-4, an essential technique for advanced Sudoku solving.
Chain Reasoning Series Advanced
Chain reasoning is the core theoretical foundation for advanced Sudoku techniques. This series contains 3 articles, recommended to read in order:
① Basics: Strong and Weak Links
Understanding strong links (exactly one true, one false) vs weak links (at most one true)
② Building: Alternating Rules and State Propagation
Learn chain building methods, coloring concept, and three ways to draw conclusions
③ Applications: Pattern Classification and Advanced Structures
Master open/closed chains, single-digit/bi-value/mixed chains (AIC), grouped links
Practice Makes Perfect
After learning techniques, the most important thing is to practice. Suggestions:
- Start easy: Practice beginner techniques with easy difficulty puzzles first
- Progress gradually: Challenge medium difficulty after mastering beginner techniques
- Use pencil marks: Develop the habit of marking candidates - it helps discover various techniques
- Analyze mistakes: When you make errors, review and identify missed techniques
Click here to start a Sudoku game and apply what you've learned!