Filter out all the existing book ids in the range of 0~1000, and use the current total number as the subscript, record the unused book ids, this operation can reduce many logical judgments
Filtering out all existing book ids in the range of 0 to 1000, and recording unused book ids with a total number of current valid numbers, can reduce many logical judgments
In the range of 0 ~ 1000, filter out all the existing book ids, and record the unused book ids with a current total number of valid subscripts. This operation can reduce many logical judgments<br>