Domination Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3822 Description Edward is the headmaster of Marjar University. He is enthusiastic about chess and often plays chess with his friends.…

Domination Time Limit: 8 Seconds      Memory Limit: 131072 KB      Special Judge Edward is the headmaster of Marjar University. He is enthusiastic about chess and often plays chess with his friends. What's more, he bought a large decorative chessboar…

题目链接:zoj 3822 Domination 题目大意:给定一个N∗M的棋盘,每次任选一个位置放置一枚棋子,直到每行每列上都至少有一枚棋子,问放置棋子个数的期望. 解题思路:大白书上概率那一张有一道类似的题目,可是由于时间比較久了,还是略微想了一下. dp[i][j][k]表示i行j列上均有至少一枚棋子,而且消耗k步的概率(k≤i∗j),由于放置在i+1~n上等价与放在i+1行上,同理列也是如此.所以有转移方程: dp[i][j][k+1]+=dp[i][j][k]∗(n−k)(S−k) d…

原题链接:http://acm.hdu.edu.cn/showproblem.php?pid=4870 原题: Rating Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 654    Accepted Submission(s): 415 Special Judge Problem Description    A little…

题目链接 495. Kids and Prizes Time limit per test: 0.25 second(s)Memory limit: 262144 kilobytes input: standardoutput: standard ICPC (International Cardboard Producing Company) is in the business of producing cardboard boxes. Recently the company organiz…

题意: 一个棋盘假设每行每列都有棋子那么这个棋盘达到目标状态  如今随机放棋子  问达到目标状态的期望步数 思路: 用概率来做  计算第k步达到目标状态的概率  进而求期望  概率计算方法就是dp  dp[k][i][j]表示第k步有i行被覆盖j列被覆盖  转移仅仅有4种  -- 同一时候覆盖行列  覆盖行  覆盖列  不覆盖  状态数50^4  非常easy 代码: #include<cstdio> #include<iostream> #include<cstring&g…

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…

B - Card Time Limit:5000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u Submit Status Description There are x cards on the desk, they are numbered from 1 to x. The score of the card which is numbered i(1<=i<=x) is i. Every round Bi…

/ dp求期望的题. 题意:一个软件有s个子系统,会产生n种bug. 某人一天发现一个bug,这个bug属于某种bug,发生在某个子系统中. 求找到所有的n种bug,且每个子系统都找到bug,这样所要的天数的期望. 需要注意的是:bug的数量是无穷大的,所以发现一个bug,出现在某个子系统的概率是1/s, 属于某种类型的概率是1/n. 解法: dp[i][j]表示已经找到i种bug,并存在于j个子系统中,要达到目标状态的天数的期望. 显然,dp[n][s]=0,因为已经达到目标了.而dp[0][…

Collecting Bugs Time Limit: 10000MS   Memory Limit: 64000K Total Submissions: 3523   Accepted: 1740 Case Time Limit: 2000MS   Special Judge Description Ivan is fond of collecting. Unlike other people who collect post stamps, coins or other material s…