题意:有m个1~n的映射,而且对于任意的 i 满足 f1(f2(...fm(i))) = i 其中有些映射是知道的,有些是不知道的,问一共有多少种置换的组合. 分析: 首先这些置换一定是1~n的一个置换(也就是1~n的一个排列)才行,因为如果某两个数映射到同一个数的话,那么这个数往后无论怎么映射,这两个数最终映射的结果还是一样的. 如果所有的f都给出来的话,那么只要判断一下就行. 如果有一个置换不知道的话,这个置换是可以通过前后的置换计算出来的,所以只有唯一解. 如果有两个置换不知道的话,第一个…

题 Description Rhason Cheung had a simple problem, and asked Teacher Mai for help. But Teacher Mai thought this problem was too simple, sometimes naive. So she ask you for help. Teacher Mai has m functions f1,f2,...,fm:{1,2,...,n}→{1,2,...,n}(that mea…

对长为L的棒子随机取一点分割两部分,抛弃左边一部分,重复过程,直到长度小于d,问操作次数的期望. 区域赛的题,比较基础的概率论,我记得教材上有道很像的题,对1/len积分,$ln(L)-ln(d)+1$. /** @Date : 2017-10-06 14:32:03 * @FileName: HDU 5984 数学期望.cpp * @Platform: Windows * @Author : Lweleth (SoungEarlf@gmail.com) * @Link : https://gi…

pid=5399">[HDOJ 5399]Too Simple 函数映射问题 给出m函数 里面有0~m个函数未知(-1) 问要求最后1~n分别相应仍映射1~n 有几种函数写法(已给定的函数不可变 仅仅可更改未知的函数的映射) 假设映射过程中出现多对一 即入度n出度小于n 的函数 必然冲突 即最后必有落单 映射失败 为0 假设映射完整 已知的连续函数可压缩成一个函数 中间出入度可忽略 因此可压缩为-1 f -1 -1 f -1 -1 f这样的形态 进一步深入可发现中间的f仅仅起到通道作用 就…

Too Simple Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Problem Description Rhason Cheung had a simple problem, and asked Teacher Mai for help. But Teacher Mai thought this problem was too simple, sometimes naiv…

1.题目描写叙述:点击打开链接 2.解题思路:本题分情况讨论.比赛时候真是想的太简单了.以为就是(n!)^(cnt-1). 终于无限WA. 本题有几个特殊情况须要额外推断. 首先,假设输入的时候.有某一行不是-1且有两个数映射到同一个数,那么必定无解,ans=0.其次.假设不存在-1,须要从第m个函数一步步映射到第1个函数,检查一下最后是否真的变成了自身映射.最easy想到的情况就是有至少一个-1,那么最后答案就是(n!)^(cnt-1). 3.代码: //#pragma comment(lin…

Simple Addition Expression Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1723    Accepted Submission(s): 675 Problem Description A luxury yacht with 100 passengers on board is sailing on the s…

http://acm.hdu.edu.cn/showproblem.php?pid=5795 A Simple Nim Problem Description   Two players take turns picking candies from n heaps,the player who picks the last one will win the game.On each turn they can pick any number of candies which come from…

题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5349 MZL's simple problem Description A simple problemProblem DescriptionYou have a multiple set,and now there are three kinds of operations:1 x : add number x to set2 : delete the minimum number (if the…

A Simple Game Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 1487    Accepted Submission(s): 939 Problem Description Agrael likes play a simple game with his friend Animal during the classes. I…