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# Anti-Addiction Sudoku

Solve All the Sudoku, Leave No Joy for Solving by Yourself

Naked Single Easy
A cell has only one candidate left — fill it in. This happens when all other digits are already present in the cell's row, column, or 3×3 box.
Example: a cell in row 3 — digits 1, 2, 4, 5, 6, 7, 8, 9 all appear nearby, so it must be 3.
Hidden Single Easy
A digit can go in only one cell within a row, column, or box — even if that cell has other candidates. It's "hidden" among them.
Example: digit 7 can only fit in one cell in a box because every other cell in that box conflicts with a 7 elsewhere in its row or column.
Naked Pairs / Triples Hard
If 2 cells in a group share exactly the same 2 candidates, no other cell in that group can hold those digits — eliminate them everywhere else. Extends to 3 cells sharing 3 candidates (Naked Triple).
Example: two cells in a row both have only {4, 9} as candidates → 4 and 9 can be removed from every other cell in that row.
Hidden Pairs / Triples Hard
If 2 digits appear as candidates in only the same 2 cells of a group, those 2 cells must contain those digits — so all other candidates in those cells can be removed.
Example: digits 3 and 8 appear only in cells A and B within a column → cells A and B cannot contain any digit other than 3 or 8.
Pointing Pairs Hard
If a digit's candidates within a 3×3 box all fall on the same row or column, that digit cannot appear in that row or column outside the box.
Example: digit 5 can only go in row 2 within a box → all other 5s in row 2 outside that box are eliminated.
X-Wing Master
When a digit appears as a candidate in exactly 2 cells in each of 2 rows, and those cells share the same 2 columns, the digit must be in one of those columns — so it can be eliminated from every other cell in those columns.
Example: digit 6 is a candidate only in columns 2 and 7 of rows 1 and 5 → 6 can be removed from all other cells in columns 2 and 7.
Swordfish Master
The X-Wing pattern extended to 3 rows and 3 columns. If a digit's candidates in 3 rows cover at most 3 columns, that digit can be eliminated from those 3 columns everywhere else.
Example: digit 2 appears only in columns 1, 4, and 8 across rows 2, 6, and 9 → 2 is removed from all other cells in columns 1, 4, and 8.
Backtracking Master
When no logical technique applies, try the most-constrained cell (fewest candidates), guess a value, and continue solving. If a contradiction is reached, undo and try the next candidate. Guaranteed to find a solution but not human-like.