james333 发表于 2021-5-31 20:51 If you group FF together, you only have 6 different letters, i.e. 6! is enough.
举报
发表回复
手机版|ChaseDream|GMT+8, 2025-7-18 16:07 京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
ChaseDream 论坛
© 2003-2025 ChaseDream.com. All Rights Reserved.