Using only kings, and as few rooks as possible, set up a position where 30 of black's kings are checkmated.
- The king is in check
- The king has no moves out of check
Black only has kings, exactly 30 of them. White has rooks and kings, and the goal is to use as few rooks as possible.
- White must have at least one king, but can have more than one.
- White kings and black kings can not stand next to each other.
- All black kings must be checkmated, stalemate is not enough.
Left: NOT valid. The king on g8 is checkmated, but the king on h8 is merely stalemated.
Right: A valid solution for 2 kings with 1 rook.
Left: NOT valid. Either king can capture the rook.
Right: A valid solution for 3 kings with 2 rooks.