题目大意:有编号为0-n的格子,从0开始,扔骰子扔到几就走几格.有m个瞬移点,每个点可以从格x直接飞到格y,若瞬移到另一个瞬移点可以继续瞬移.求到达格n的期望扔骰子次数. 题解:期望DP入门好题.网上神犇们都说,“经验表明,一般情况下,求期望的题从后往前推.”本蒟蒻一开始不明白,谁给你的权利一定要从后往前啊!于是我就写了这样一个式子: E(i)——到格i期望,E(i)=i是某个瞬移目标点?(E(x),x指瞬移出发点),否则E(i-1)*1/6+E(i-2)*1/6+...+E(i-6)*1/6+…

http://acm.split.hdu.edu.cn/showproblem.php?pid=4405 Aeroplane chess Problem Description   Hzz loves aeroplane chess very much. The chess map contains N+1 grids labeled from 0 to N. Hzz starts at grid 0. For each step he throws a dice(a dice have six…

Aeroplane chess Time Limit: 1 Sec  Memory Limit: 32 MB[Submit][Stataus][Discuss] Description Hzz loves aeroplane chess very much. The chess map contains N+1 grids labeled from 0 to N. Hzz starts at grid 0. For each step he throws a dice(a dice have s…

类型:概率DP 题意:一条直线下飞行棋,色子六个面等概率.同时存在一些飞机航线,到了某个点可以直接飞到后面的另一个点,可以连飞,保证一个点至多一条航线.求到达或者超过终点 所需要 掷色子的期望次数. 思路: 如果可以飞,那么从这个点到终点的期望次数 等于 飞到的那个点 到终点的期望次数. 否则,就是掷一次色子,然后后面六个点到终点的期望次数 求平均 +1; 换种表示: if (canFly) dp[now] = dp[flyTo]; else dp[now] = (dp[now+1]+dp[no…

http://acm.hdu.edu.cn/showproblem.php?pid=4405 看了一下这个博客http://kicd.blog.163.com/blog/static/126961911200910168335852/ Aeroplane chess Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1336    Acce…

题目: Problem Description Hzz loves aeroplane chess very much. The chess map contains N+1 grids labeled from 0 to N. Hzz starts at grid 0. For each step he throws a dice(a dice have six faces with equal probability to face up and the numbers on the fac…

Aeroplane chess Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1597    Accepted Submission(s): 1088 Problem Description Hzz loves aeroplane chess very much. The chess map contains N+1 grids lab…

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…

概率DP/数学期望 kuangbin总结中的第4题 啊还是求期望嘛……(话说Aeroplane chess这个翻译怎么有种chinglish的赶脚……) 好像有点感觉了…… 首先不考虑直飞的情况: f[i]表示从第 i 格到end的期望掷骰子次数,那明显就是从f[i+1]~f[i+6]各1/6的概率(系数) 转移过来啦~ 那直飞呢? so easy,f[i]=f[fly[i]]即可,其中fly[i]表示从第 i 格飞到的格子.当然直飞就不用再考虑1/6的掷骰子情况了…… 从n-1往0逆推即可 P…

Aeroplane chess Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 1503    Accepted Submission(s): 1025 Problem Description Hzz loves aeroplane chess very much. The chess map contains N+1 grids la…