Place one of the four letters A, B, C or D in each of the blue-coloured cells. No letter can be horizontally or vertically adjacent to itself. The yellow-coloured tables above and to the left of the grid indicate how many times each letter appears in that column or row.
This is an extended version of ABCD.
| | | | | | | | | | | | | | | |
| | | | A | 3 | 2 | 0 | 2 | 2 | 2 | 0 | 3 | 1 | | |
| | | | B | 2 | 1 | 3 | 0 | 0 | 1 | 3 | 0 | 2 | | |
| | | | C | 1 | 2 | 1 | 3 | 2 | 3 | 1 | 2 | 1 | | |
| A | B | C | D | 0 | 1 | 2 | 1 | 2 | 0 | 2 | 1 | 2 | | |
| 2 | 0 | 4 | 3 | | | | | | | | | | | |
| 4 | 4 | 1 | 0 | | | | | | | | | | | |
| 3 | 2 | 2 | 2 | | | | | | | | | | | |
| 3 | 3 | 2 | 1 | | | | | | | | | | | |
| 1 | 0 | 4 | 4 | | | | | | | | | | | |
| 2 | 3 | 3 | 1 | | | | | | | | | | | |
| | | | | | | | | | | | | | | |
The required arrangement is as follows:
A..C..D..C..A..C..D..C..D
B..A..B..A..C..A..B..A..B
A..B..D..C..A..B..C..D..A
B..A..B..A..D..C..B..A..C
C..D..C..D..C..A..D..C..D
A..C..B..C..D..C..B..A..B
Answer
