PlaySudoku.us
Hard · Puzzle #635
3
1
9
2
9
4
3
7
2
8
7
8
6
5
4
4
2
1
4
5
6
9
2
2
1
6
8
7
Graph coloring and Sudoku are equivalent problems. Each cell is a node; edges connect cells that share a house. Solving Sudoku = coloring the graph with 9 colors.
Graph coloring and Sudoku are equivalent problems. Each cell is a node; edges connect cells that share a house. Solving Sudoku = coloring the graph with 9 colors.
Naked Pairs: if two cells in a house share the same two candidates, eliminate those digits from all other cells in that house.
Naked Pairs: if two cells in a house share the same two candidates, eliminate those digits from all other cells in that house.