The program generates random puzzle and tries to solve it. Example of work:
2 3 7 4
6 11 14 8
1 13 12
9 5 10 15
-=========-
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15
1 2 3 4
5 6 7 8
9 11 12
13 10 14 15
1 2 3 4
5 6 7 8
9 11 12
13 10 14 15
1 2 3 4
6 7 8
5 9 11 12
13 10 14 15
2 3 4
1 6 7 8
5 9 11 12
13 10 14 15
2 3 4
1 6 7 8
5 9 11 12
13 10 14 15
2 3 4
1 6 7 8
5 9 11 12
13 10 14 15
2 3 7 4
1 6 8
5 9 11 12
13 10 14 15
2 3 7 4
1 6 11 8
5 9 12
13 10 14 15
2 3 7 4
1 6 11 8
5 9 14 12
13 10 15
2 3 7 4
1 6 11 8
5 9 14 12
13 10 15
2 3 7 4
1 6 11 8
5 9 14 12
13 10 15
2 3 7 4
1 6 11 8
9 14 12
5 13 10 15
2 3 7 4
1 6 11 8
9 14 12
5 13 10 15
2 3 7 4
1 6 11 8
9 13 14 12
5 10 15
2 3 7 4
1 6 11 8
9 13 14 12
5 10 15
2 3 7 4
1 6 11 8
13 14 12
9 5 10 15
2 3 7 4
6 11 8
1 13 14 12
9 5 10 15
2 3 7 4
6 11 8
1 13 14 12
9 5 10 15
2 3 7 4
6 11 8
1 13 14 12
9 5 10 15
2 3 7 4
6 11 14 8
1 13 12
9 5 10 15
length: 23