21 clues.

- Code: Select all
`. . . . 3 2 9 . .`

. . . 5 . . . 6 .

. . 1 7 . . . . 8

. 5 7 6 . . . . .

3 . . . 9 . . . .

2 . . . . 4 . . .

9 . . . . . 2 . .

. 6 . . . . . 5 .

. . 8 . . . . . 1

Part one :

It has 2 types of symmetry with the main diagonal :

pattern-symmetry

digits-symmetry

This puzle has exactly 2 solutions.

50 cells differ in the two solutions ; only 10 are the same.

More precisely :

Given clues : 21

Cells that differ in two solutions : 50

Cells that are the same : 10

see here.

Common cells (x) for the 2 solutions :

- Code: Select all
`x . . | . 3 2 | 9 x .`

. x . | 5 . x | . 6 .

. . 1 | 7 x x | . . 8

-------+-------+-------

. 5 7 | 6 . . | . . .

3 . x | . 9 . | . . .

2 x x | . . 4 | . . .

-------+-------+-------

9 . . | . . . | 2 . .

x 6 . | . . . | . 5 .

. . 8 | . . . | . . 1

6 in r1c1 can be obtained by SST

The 9 other cells (actually 5 due to the symmetry) need more advanced techniques.

Any solvers for these cells ?

JPF