????1.??????漰???洢???????????????????????
????2.????????????
?????????????????????????????????????н????????????????????к????????????????
????3.?????????????
????a.?????????е????????
????i.?????????????2???????????????
????ii.??????????к??
????iii.??臨??????T(N)=2T(N/2)+O(N);????T(N)?N???????????????????T(N/2)?N/2???????????????????????O(N)??????????????????T(N)=O(N*logN)?????????O(N^2)?????????
????b.??????????Σ?
????i.??C=A*B?????A???з??n???B???з??m??
????ii.C?????Cn=An*B1??An*B2??...??An*Bm
????Cnm=An*Bm
??????Cnm????Cn???????
????iii.??????10?????????????????????10??
????c.????——Map??????——Reduce