摘要：Aeroplane chess Aeroplane chess Hzz loves aeroplane chess very much. The chess map contains N+1 grids labeled from 0 to N. Hzz starts at grid 0. For e 阅读全文

摘要：Walk I used to think I could be anything, but now I know that I couldn't do anything. So I started traveling. The nation looks like a connected bidire 阅读全文

摘要：题意有n个硬币排成一排，开始的时候所有的硬币都是正面朝下，你必须要扔K次硬币，每次选择一个硬币，如果你采取最优策略，K次以后朝上的硬币数的最大期望是多少？ 随机变量X是指朝上的硬币数，当有N枚硬币的时候，X=0，1，2，3....N E(X)=1*p(1)+2*p(2)+....+n*p(n)。 要 阅读全文