# 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 Mar 27 '20 at 12:18
• Oooh cool! I will try 6x6 Now... Mar 27 '20 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. Mar 27 '20 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... Mar 27 '20 at 16:28
• Wow! I could not find 7 queens with my program. Mar 27 '20 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