A complete Sudoku strategy is a solving loop, not a bag of tricks.
A technique proves one kind of move. A strategy tells you when to search for it, when to stop, and what to check again after the grid changes. Use this six-stage loop on every puzzle.
Sudoku strategy, defined
A Sudoku strategy is an ordered process for choosing the next logical search. Start with the cheapest reliable checks, apply one proved placement or elimination, then restart because the changed grid may reveal an easier move.
The six-stage solving strategy
A placement or elimination changes candidate lists. That change can create a single, a pointing pair, or a smaller group. Restart the simple loop before continuing the advanced search; otherwise you do extra work and risk carrying a stale pattern.
- 01
Scan rows, columns, and boxes
Find missing digits and crossing constraints. Start with the fullest areas and place only what the current grid proves.
See the worked example → - 02
Write and maintain candidates
When scanning stalls, record every legal digit in the relevant empty cells. Update notes after every placement.
See the worked example → - 03
Clear every forced move
Look for cells with one candidate and digits with one possible cell. Repeat across the whole grid.
See the worked example → - 04
Use intersections and groups
Check pointing pairs, claiming candidates, naked pairs, hidden pairs, and then triples before escalating.
See the worked example → - 05
Follow one digit across the grid
Map one candidate for short links, X-Wing, and Swordfish. Reject a pattern as soon as one required count fails.
See the worked example → - 06
Bound wings, coloring, and chains
Use a finite pivot or link search. After any elimination, return immediately to scanning and singles.
See the worked example →
The restart rule matters more than the advanced name.
A placement or elimination changes candidate lists. That change can create a single, a pointing pair, or a smaller group. Restart the simple loop before continuing the advanced search; otherwise you do extra work and risk carrying a stale pattern.
Open the technique library when a stage is unfamiliar.
Each reference gives a concise definition, difficulty level, worked board, exact proof, related methods, and a handoff to the real interactive lesson.
Browse every Sudoku technique →Use the strategy on the grid that stopped you.
Bring a screenshot, photo, or typed grid. Doku.su starts with where to look and lets you reveal the reason one step at a time.
Use my Sudoku →A library published by Doku.su
Every public placement or elimination example is tied to the Doku.su curriculum and checked by its deterministic Sudoku engine. English and French pages use the same proof model.
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