Find the minimum and maximum number of clues of valid puzzles such that:

- r9c1=r1c9=0

- if ricj=0 then r(i+1)c(j+1)=0

- if 0<ricj<8 then r(i+1)c(j+1)={(ricj)+1} or 0

- if ricj=9 then r(i+1)c(j+1)= 1 or 0

Here is an example 25c:

- Code: Select all
`+-------+-------+-------+`

| 1 . . | 2 . . | . 4 . |

| . 2 . | . 3 . | . . 5 |

| . . 3 | . . 4 | . . . |

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

| 7 . . | 4 . . | 5 . . |

| . 8 . | . 5 . | . 6 . |

| . . 9 | . . 6 | . . 7 |

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

| 4 . . | 1 . . | 7 . . |

| . 5 . | . 2 . | . 8 . |

| . . 6 | . . . | . . 9 |

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

JPF