It does not matter! The key is...

来源: 于 2009-04-30 10:29:14 [旧帖] [给我悄悄话] 本文已被阅读：次

The colors of the diagonal squares do not matter. A non-red diagonal square needs to contact only one red square, and a red square needs to contact only one red square as well. The key is a diagonal square does not side-contact any other diagonal square.