3 ms·

The number of unique 5x5 grids is 33,554,432 (2^25) and the number if you ignore rotation or reflection is 4,211,744. What is 28,781,820?

• duskwuff 1y ago
  That's the number of unique combinations of clues for all 2^25 puzzles. There are 13 possible clues for each row/column (0 1 2 3 4 5 11 12 13 21 22 31 111), but not all 13^10 possible combinations can appear together - for instance, 5 5 5 5 5 / 0 0 0 0 0 is obviously impossible. (I wrote a program to calculate this by generating all 2^25 puzzles and their clues, then sorting by the clues. I also verified the count of 25,309,575 clues with unique solutions.)
  • ghusbands 1y ago
    That's great, thanks. I've also independently verified the 25,309,575 using similar techniques.
  • deleted 1y ago
    [deleted]