Detail of message

Online Judge

Problem Set

Authors

Online Contests

User

Web Board
Home Page
F.A.Qs
Statistical Charts

Current Contest
Past Contests
Scheduled Contests
Award Contest

求天数期望我是看明白了，就是K个几何分布加起来。可是第二个答案没看懂，总钱数和方差有什么关系？

Posted by ImLazy at 2008-09-16 14:36:06 on Problem 3682 and last updated at 2008-09-16 14:37:23
In Reply To:那就给个简单推导吧 Posted by:Cpp at 2008-09-01 00:09:05

Followed by:

哦，钱数的算法我也明白了。1+3+5+...+(2n-1) = n^2，钱数的期望正好变成天数的平方的期望，于是就可以用Dx = Ex^2 - E(x^2)来算了。我反应真慢。 (0) ImLazy 2008-09-16 14:57:58

Post your reply here:

Home Page Go Back To top