Can two queens from the same colour atack each other? If they can't then the

answer is

They can't

Ok, Then the answer is 3. It is easy to see that the max of 2n is 8. I didn't find any solution for 8. So the answer is 2n=6. n=3 PS: try to see if 2n can be 8.

TurtleKing123 wrote: Can two queens from the same colour atack each other? If they can't then the

answer is

it's obvious that $n\le 4$

I would guess that the correct formulation is: * Two queens of DIFFERENT colors are NOT ALLOWED to attack each other. * Two queens of the SAME color MAY attack each other. (If queens of different colors and queens of same color must not attack each other, the colors would be irrelevant. The problem would simply ask for $2n$ queens that do not attack each other.)

Two queens attack each other when they have different colors. The queens of the same color don't attack each other.

Then $n=8$ is certainly possible: Place eight white queens on the eight squares a1, a2, a3, b1, b2, b3, and c2, c3. There are nine squares that are not attacked by any of these eight queens, and that hence can accommodate black queens.

test20 wrote: I would guess that the correct formulation is: * Two queens of DIFFERENT colors are NOT ALLOWED to attack each other. * Two queens of the SAME color MAY attack each other. (If queens of different colors and queens of same color must not attack each other, the colors would be irrelevant. The problem would simply ask for $2n$ queens that do not attack each other.) 我觉得你是错的，但这件事用英语很难说。 很明显题目与颜色是有关系的，因为它不仅要求2n个皇后不能相互攻击，还要求其中有一半在白格，一半在黑格。