题意:一个人若连续进k1个球或连续不进k2个球,游戏结束,给出这个人不进球的概率p(注意:是不进球!!!),求到游戏结束时这个投球个数的期望. 不进球概率为p,进概率 q=1-p.设 f[i] 表示连续 i 次不进结束的期望,t[i]表示连续 i 次进球,距离结束的期望.显然,f[k2]=t[k1]=0;f[i] = q*(f[i+1]+1)+p*(1+t[1]) , t[i] = p*(t[i+1]+1)+q*(1+f[1]). 答案是 p*t[1]+q*f[1]+1.然后就算t[1],f[1…

题意:一个人若连续进k1个球或连续不进k2个球,游戏结束,给出这个人进球的概率p,求到游戏结束时这个投球个数的期望. 进球概率为p,不进概率 q=1-p 设 f[i] 表示连续 i 次不进距离连续k2次不进结束的期望,t[i]表示连续 i 次进球,距离连续k1次进球结束的期望.显然,f[k2]=p[k1]=0; f[i] = q*(f[i+1]+1)+p*(1+t[1]) , t[i] = p*(t[i+1]+1)+q*(1+f[1]). 答案是 p*t[1]+q*f[1]+1. 然后就算t[1…

LOOPS Time Limit: 15000/5000 MS (Java/Others)    Memory Limit: 125536/65536 K (Java/Others) Total Submission(s): 1864    Accepted Submission(s): 732 Problem Description Akemi Homura is a Mahou Shoujo (Puella Magi/Magical Girl). Homura wants to help h…

借鉴自:https://www.cnblogs.com/keyboarder-zsq/p/6216762.html 题意:n个格子,每个格子有一个值.从1开始,每次扔6个面的骰子,扔出几点就往前几步,然后把那个格子的金子拿走: 如果扔出的骰子+所在位置>n,就重新扔,直到在n: 问取走这些值的期望值是多少 解析: [1] [2] [3][4] [5] [6] [7] [8] [9] //格子和值都是一样,所以下述的话,值就是格子,格子就是值... 比如这样的9个格子,我们总底往上来 对于第9个格…

D - Joyful Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Description Sakura has a very magical tool to paint walls. One day, kAc asked Sakura to paint a wall that looks like an $M \times N$ matrix. The wal…

Collecting Bugs Ivan is fond of collecting. Unlike other people who collect post stamps, coins or other material stuff, he collects software bugs. When Ivan gets a new program, he classifies all possible bugs into n categories. Each day he discovers…

题目大意:在nxm的方格中,从(1,1)走到(n,m).每次只能在原地不动.向右走一格.向下走一格,概率分别为p1(i,j),p2(i,j),p3(i,j).求行走次数的期望. 题目分析:状态转移方程很容易得到: E(i,j)=p1(i,j)*E(i,j)+p2(i,j)*E(i,j+1)+p3(i,j)*E(i+1,j). 代码如下: # include<iostream> # include<cstdio> # include<cmath> # include<…

Aeroplane chess Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1667    Accepted Submission(s): 1123 Problem Description Hzz loves aeroplane chess very much. The chess map contains N+1 grids lab…

C - Collecting Bugs Time Limit:10000MS     Memory Limit:64000KB     64bit IO Format:%I64d & %I64u Submit Status Description Ivan is fond of collecting. Unlike other people who collect post stamps, coins or other material stuff, he collects software b…

D - LOOPS Time Limit:5000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Description Akemi Homura is a Mahou Shoujo (Puella Magi/Magical Girl). Homura wants to help her friend Madoka save the world. But because of the plot…