Scanning every customer is approximately o (m), not o (MN), because almost all customer vectors contain a small number of items, regardless of the size of the catalog.

扫描每一个顾客大约是O (M)，而不是O (MN)，因为几乎所有顾客向量都只含有很少的商品，无需考虑产品目录的规模。

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Objective To establish a method for genotyping of MN blood group and detect the allele frequencies of M and N in population.

目的建立MN血型系统基因分型的方法，检测人群中MN基因的频率。

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