输出保留 3 位小数的浮点数

Status	Submit By	Time	Memory	Language	Code	Submit At
AC	龙肖瑾xly2025	34ms	768 KiB	C++14(O2)	142 Bytes	2025-7-27 22:03:20
AC	若白	35ms	764 KiB	C++17(O2)	122 Bytes	2025-7-11 14:37:50
AC	maochengjun	35ms	808 KiB	C++14	141 Bytes	2025-7-9 11:38:05
AC	陈国瑞	36ms	804 KiB	C++14(O2)	150 Bytes	2025-7-15 17:17:29
AC	xzh13579	36ms	808 KiB	C++14(O2)	188 Bytes	2025-7-24 23:22:09
AC	张芷若xly2025	36ms	908 KiB	C++14(O2)	144 Bytes	2025-8-8 8:33:57
AC	_chjich_	38ms	808 KiB	C++14(O2)	122 Bytes	2025-7-11 9:31:38
AC	曾彦彬contest	38ms	812 KiB	C++14(O2)	166 Bytes	2025-7-7 19:41:20
AC	女乃龙	38ms	868 KiB	C++14(O2)	141 Bytes	2025-7-11 14:41:35