The full reasoning can be found below the Sudoku.
Apr 01 - Super Hard
Puzzle Copyright © Kevin Stone
Share link:
Reasoning
R5C5 can only be <6>
R8C1 can only be <1>
R8C4 can only be <8>
R1C8 is the only square in row 1 that can be <2>
R4C8 can only be <1>
R2C5 is the only square in row 2 that can be <8>
R2C4 is the only square in row 2 that can be <5>
R7C4 can only be <1>
R3C4 can only be <6>
R2C3 is the only square in row 2 that can be <1>
R3C5 is the only square in row 3 that can be <1>
R3C6 is the only square in row 3 that can be <2>
R5C2 is the only square in row 5 that can be <1>
R8C3 is the only square in row 8 that can be <6>
R6C3 can only be <8>
R5C8 is the only square in row 5 that can be <8>
R7C2 is the only square in row 7 that can be <8>
Intersection of row 2 with block 3. The value <3> only appears in one or more of squares R2C7, R2C8 and R2C9 of row 2. These squares are the ones that intersect with block 3. Thus, the other (non-intersecting) squares of block 3 cannot contain this value.
R3C7 - removing <3> from <3479> leaving <479>
R3C8 - removing <3> from <379> leaving <79>
Intersection of column 8 with block 9. The value <3> only appears in one or more of squares R7C8, R8C8 and R9C8 of column 8. These squares are the ones that intersect with block 9. Thus, the other (non-intersecting) squares of block 9 cannot contain this value.
R7C7 - removing <3> from <3579> leaving <579>
R8C7 - removing <3> from <2379> leaving <279>
R8C9 - removing <3> from <239> leaving <29>
R8C5 is the only square in row 8 that can be <3>
Squares R1C2 and R1C5 in row 1 and R9C2 and R9C5 in row 9 form a Simple X-Wing pattern on possibility <4>. All other instances of this possibility in columns 2 and 5 can be removed.
R3C2 - removing <4> from <3479> leaving <379>
R7C5 - removing <4> from <457> leaving <57>
Squares R2C6 and R2C7 in row 2 and R8C6 and R8C7 in row 8 form a Simple X-Wing pattern on possibility <7>. All other instances of this possibility in columns 6 and 7 can be removed.
R3C7 - removing <7> from <479> leaving <49>
R7C6 - removing <7> from <479> leaving <49>
R7C7 - removing <7> from <579> leaving <59>
Squares R7C5 (XY), R7C7 (XZ) and R8C6 (YZ) form an XY-Wing pattern on <9>. All squares that are buddies of both the XZ and YZ squares cannot be <9>.
R8C7 - removing <9> from <279> leaving <27>
R8C9 - removing <9> from <29> leaving <2>
R7C6 - removing <9> from <49> leaving <4>
R7C3 can only be <3>
R2C6 can only be <7>
R9C5 can only be <5>
R8C7 can only be <7>
R9C8 can only be <3>
R7C5 can only be <7>
R9C2 can only be <4>
R8C6 can only be <9>
R1C5 can only be <4>
R1C2 can only be <7>
R4C2 can only be <6>
R3C3 can only be <4>
R3C7 can only be <9>
R5C3 can only be <2>
R2C1 can only be <9>
R3C2 can only be <3>
R3C8 can only be <7>
R7C7 can only be <5>
R2C9 can only be <3>
R4C7 can only be <2>
R6C2 can only be <9>
R4C3 can only be <7>
R5C7 can only be <3>
R5C9 can only be <9>
R2C7 can only be <4>
R5C1 can only be <4>
R6C8 can only be <5>
R6C7 can only be <6>
R7C8 can only be <9>
Today's Sudoku Puzzles
All daily items change at midnight GMT – set your local time zone.
Note: BrainBashers has a Dark Mode option – I recommend not using your browser's dark mode or extensions for BrainBashers