DZY Loves Balls 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5645 Description DZY loves playing balls. He has n balls in a big box. On each ball there is an integer written. One day he decides to pick two balls from the box. First he randomly pick…

DZY Loves Balls  Accepts: 659  Submissions: 1393  Time Limit: 4000/2000 MS (Java/Others)  Memory Limit: 262144/262144 K (Java/Others) 问题描述 DZY喜欢玩球. 他有nn个球,装进一个大盒子里.每个球上面都写着一个整数. 有一天他打算从盒子中挑两个球出来.他先均匀随机地从盒子中挑出一个球,记为AA.他不把AA放回盒子,然后再从盒子中均匀随机地挑出一个球,记为BB.…

DZY Loves Balls Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 807    Accepted Submission(s): 439 Problem Description There are n black balls and m white balls in the big box. Now, DZY starts…

//yy:那天考完概率论,上网无聊搜个期望可加性就搜到这题,看到以后特别有亲和感,挺有意思的. hdu5194 DZY Loves Balls [概率论 or 搜索] 题意: 一个盒子里有n个黑球和m个白球[n,m≤12].每次随机从盒子里取走一个球,取了n+m次后,刚好取完.现在用一种方法生成了一个随机的01串S[1…(n+m)],如果第i次取出的球是黑色的,那么S[i]=1,如果是白色的,那么S[i]=0.求'01'在S串中出现的期望次数. 题解: 求出在第i个位置上出现0,第i+1个位置上…

题目链接: hdu:http://acm.hdu.edu.cn/showproblem.php?pid=5646 bc:http://bestcoder.hdu.edu.cn/contests/contest_chineseproblem.php?cid=680&pid=1002 DZY Loves Connecting Accepts: 16     Submissions: 169 Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 26…

DZY Loves Partition 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5646 Description DZY loves partitioning numbers. He wants to know whether it is possible to partition n into the sum of exactly k distinct positive integers. After some thinking he f…

DZY Loves Topological Sorting Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5195 Description A topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for ev…

传送门 DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 221    Accepted Submission(s): 52 Problem Description A topological sort or topological ordering of a directed…

DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 866    Accepted Submission(s): 250 Problem Description A topological sort or topological ordering of a directed g…

DZY Loves Sorting Time Limit: 12000/6000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 294    Accepted Submission(s): 77 Problem Description DZY has a sequence a[1..n]. It is a permutation of integers 1∼n. Now he…