2019ACM-ICPC沈阳网络赛-K-Guanguan's Happy water

Guanguan's Happy water

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Rather than drinking happy water, Guanguan loves storing happy water. So he bought a refrigerator and stored a_iai​ bottles of cola into it every day. When the storage is finished on the kk-th day, the refrigerator is full, but he still wants to store happy water every day. Here comes the solution: He first constructs a p-sequence: p_1p1​, p_2p2​, ..., p_kpk​, where p_1+p_2+...+p_k=1p1​+p2​+...+pk​=1. Then he chooses an number ii among 11 to kk, where number ii has the probability p_ipi​ to be chosen. After that, he drinks the happy water stored on the ii-th day before the current day and stores the same amount of happy water back into the refrigerator again. Let the amount of happy water stored on the ii-th day be f_ifi​. Given the amount of happy water stored in the first kk days and the expected amount of the next kk days(which means, from the k+1k+1-th day to the 2k2k-th day), could you help Guanguan figure out the sum of the expected amount of happy water stored during the first n

转载于:https://www.cnblogs.com/CharlieWade/p/11519645.html