[fix] better solution for handling empty result (#1796)

Xingchen Song(宋星辰)

2024-06-11 0bd1a4d6a9893e45438505514a063d9deee91f21

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C    1
CC    2
CCC    3
CD    4
D    5
DC    6
DCC    7
DCCC    8
CM    9