输出保留 3 位小数的浮点数

Status	Submit By	Time	Memory	Language	Code	Submit At
AC	admin	19ms	20.4 MiB	C++14	168 Bytes	2026-8-28 16:17:46
AC	ALT_liangweizhen	20ms	20.4 MiB	C++14	134 Bytes	2026-11-10 19:49:23
AC	ALT_wanglinxuan	20ms	20.4 MiB	C++14	139 Bytes	2026-11-9 20:45:52
AC	ALT_sunshuoran	20ms	20.4 MiB	C++14	120 Bytes	2026-9-6 11:07:22
AC	ALT_liusiyu	21ms	20.4 MiB	C++14	135 Bytes	2026-11-10 21:17:55
AC	ALT_zhangweichen	22ms	20.4 MiB	C++14	147 Bytes	2026-9-13 16:27:06
AC	ALT_xizhanxuan	22ms	20.4 MiB	C++14	136 Bytes	2026-9-21 21:13:57
AC	ALT_chejunhao	22ms	20.4 MiB	C++14	132 Bytes	2026-10-11 13:13:28
AC	ALT_wujinze	33ms	20.4 MiB	C++14	142 Bytes	2026-11-9 20:07:16