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Evil · Puzzle #467
4
9
2
7
8
5
6
9
2
8
9
3
4
5
1
3
1
4
5
8
2
6
Techniques used
- Naked Single
- Hidden Single
- Naked Pair
- Naked Triple
- Hidden Pair
- Pointing Pair
- Box-Line Reduction
- Forcing Chains
- XY-Chain
- UR Type 4
- W-Wing
The Swordfish technique extends X-Wing to three rows and three columns — rare but decisive on expert grids.
The Swordfish technique extends X-Wing to three rows and three columns — rare but decisive on expert grids.
The maximum number of givens in a Sudoku that still leaves the rest logically deducible (no trivial completion) can exceed 77.
The maximum number of givens in a Sudoku that still leaves the rest logically deducible (no trivial completion) can exceed 77.