# 4-coloured queens attacking every opponent queen once

Can you place 6 queens from four different colours (24 in total), such that each queen attacks exactly one queen of each colour? They may attack as many queens of their own colour as these are ignored.

Here is a similar question: 3 Colors of Chess Pieces Attacking Each Other Once Each

• I had a solution for this a few days ago, but I'm having trouble now...? btw: 6×6 in 106 Commented Mar 27, 2020 at 12:18
• Oooh cool! I will try 6x6 Now... Commented Mar 27, 2020 at 12:22

 A B . . . B C .
C D . . D . . C
. . . . A . . B
. . . . . A D .
. D A . . . . .
C . . A . . . .
B . . D . . D B
. B C . . . C A

• Nice solution. I have a different one which I will post later. Commented Mar 27, 2020 at 13:15

You asked for 6 queens, but the maximum is at least

• I even thought to suggest that you would find a better solution with your programming... Commented Mar 27, 2020 at 16:28
• Wow! I could not find 7 queens with my program. Commented Mar 27, 2020 at 21:24

Here is the solution I had in mind:


. . . . 3 1 . .
. . . . 4 2 . .
. 1 3 . . . . .
. 2 4 . . . 4 2
. . . . . . 3 1
4 2 . 2 4 . . .
3 1 . 1 3 . 3 1
. . . . . . 4 2