- Code: Select all
` *-----------*`

|4..|..9|6..|

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

|...|..3|..8|

|---+---+---|

|76.|...|.4.|

|.35|.2.|..7|

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

|---+---+---|

|.7.|.3.|58.|

|3..|.6.|2..|

|..1|...|...|

*-----------*

The first puzzle, above, has multiple solutions, so it is invalid.

The second puzzle, below, can be solved with nothing more than singles and a few exclusions based on line-box interactions.

- Code: Select all
` *-----------*`

|.81|.67|.24|

|2..|94.|...|

|...|...|17.|

|---+---+---|

|.7.|429|...|

|6..|1..|...|

|...|...|71.|

|---+---+---|

|5..|...|...|

|...|..6|..2|

|.23|...|.8.|

*-----------*

For example.. there is only one place in box 2 (the center top box) for a 1. Likewise only one place in box 4 for a 1. There is only one place a 2 can go in box 6. The 4 in box 6 must be in row 5, so all other 4s can be excluded from row 5. Etc. Etc.