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…

ZYB loves Score Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5268 Description One day,ZYB participated in the BestCoder Contest There are four problems. Their scores are 1000,1500,2000,2500 According to the r…

Dylans loves numbers Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5272 Description Dylans是谁?你可以在 UOJ 和 Codeforces上看到他.在BestCoder里,他有另外一个ID:s1451900.今天的题目都和他有关哦.Dylans得到了一个数N.他想知道N的二进制中有几组1.如果两个1之间有若干个(至少一个)0…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5656 CA Loves Stick Accepts: 381   Submissions: 3204 Time Limit: 2000/1000 MS (Java/Others)     Memory Limit: 262144/262144 K (Java/Others) 问题描述 CA喜欢玩木棍. 有一天他获得了四根木棍,他想知道用这些木棍能不能拼成一个四边形.(四边形定义:https://e…

//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…

L - House Building Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5538 Description Have you ever played the video game Minecraft? This game has been one of the world's most popular game in recent years. The wor…

Friendship of Frog Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5578 Description N frogs from different countries are standing in a line. Each country is represented by a lowercase letter. The distance betwee…

ZYB's Biology Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5590 Description ZYB(ZJ−267)在NOIP拿到600分之后开始虐生物题,他现在扔给你一道简单的生物题:给出一个DNA序列和一个RNA序列,问它们是否配对. DNA序列是仅由A,C,G,T组成的字符串,RNA序列是仅由A,C,G,U组成的字符串. DNA和RNA匹配当且仅当每…