Alice and Bob are playing a simple game. They line up a row of n identical coins, all with the heads facing down onto the table and the tails upward. For exactly mm times they select any k of the coins and toss them into the air, replacing each of th…

题目链接:https://www.jisuanke.com/contest/2870?view=challenges 题目大意:给出n个都正面朝下的硬币,操作m次,每次都选取k枚硬币抛到空中,求操作m次后,硬币向上的期望值. 思路: 1.期望跟概率还是有点不同的,期望要枚举出抛的所有的情况,然后求sigma(i * dp[][]) 2.dp[i][j]表示进行i次操作后,有j枚硬币向上的概率.这样就可以求最后的硬币向上的期望了. 3.值得注意的是,预处理的组合数要开 double 型. 代码:…

Alice and Bob are playing a simple game. They line up a row of nn identical coins, all with the heads facing down onto the table and the tails upward. For exactly mm times they select any kk of the coins and toss them into the air, replacing each of…

I. Older Brother Your older brother is an amateur mathematician with lots of experience. However, his memory is very bad. He recently got interested in linear algebra over finite fields, but he does not remember exactly which finite fields exist. For…

L. Sticky Situation While on summer camp, you are playing a game of hide-and-seek in the forest. You need to designate a “safe zone”, where, if the players manage to sneak there without being detected,they beat the seeker. It is therefore of utmost i…

All as we know, a mountain is a large landform that stretches above the surrounding land in a limited area. If we as the tourists take a picture of a distant mountain and print it out, the image on the surface of paper will be in the shape of a parti…

题目链接:Coins Description Alice and Bob are playing a simple game. They line up a row of nn identical coins, all with the heads facing down onto the table and the tails upward. For exactly mm times they select any kk of the coins and toss them into the…

挺不错的概率DP,看似基础,实则很考验扎实的功底 这题很明显是个DP,为什么???找规律或者算组合数这种概率,N不可能给的这么友善... 因为DP一般都要在支持N^2操作嘛. 稍微理解一下,这DP[i][j]还是不好想啊,首先是写DP[I][j]的含义 首先我们想这道题是要求一个最优决策下的期望,那么这个我们的最优决策是什么??? 决策就是:我们假设我这一次需要翻转K个硬币,我们不愿翻那些已经在正面的,而去翻那些没有在正面的 而如果剩余的反面的不足,我再去翻转正面的 那么给dp[i][j]一个含…

A. Coins Alice and Bob are playing a simple game. They line up a row of nnn identical coins, all with the heads facing down onto the table and the tails upward. For exactly mmm times they select any kkk of the coins and toss them into the air, replac…

题目:给出K个数,使得这K个数的和为N,LCM为M,问有多少种 f[i][j][k]表示选i个数,总和为j,最小公倍数为k memery卡的比较紧,注意不要开太大,按照题目数据开 这种类型的dp也是第一次做 #include<cstdio> #include<iostream> #include<algorithm> #include<cstring> #include<cmath> #include<queue> #include&…

Daydreaming Stockbroker Gina Reed, the famous stockbroker, is having a slow day at work, and between rounds of solitaire she is day-dreaming. Foretelling the future is hard, but imagine if you could just go back in time and use your knowledge of stoc…

2017 ACM ICPC Asia Regional - Daejeon Problem A Broadcast Stations 题目描述:给出一棵树,每一个点有一个辐射距离\(p_i\)(待确定),但\(p_i==0\)的点不能辐射自己,只能由别的点辐射覆盖.求\(p_i\)的和的最小值. Problem B Connect3 题目描述:有一个\(4 \times 4\)的网格,两个人玩游戏,第一个人用黑棋,第二人用白棋.每次选择一列,将棋子扔下去,直到最下一个空的格子.现在给出第一个人下…

2017 ACM - ICPC Asia Ho Chi Minh City Regional Contest A - Arranging Wine 题目描述:有\(R\)个红箱和\(W\)个白箱,将这些箱子分成若干堆,使得每一堆只有一种颜色,然后将这些堆排成一排,使得相邻的堆的颜色不一样,并且每堆红箱的个数不能超过\(d\),问有多少种方案. solution 不会. B - Barcode 题目描述:有一排\(n\)个球,现在要给这\(n\)个球涂成红色或蓝色,使得红色球的个数等于蓝色球的个数…

QSC and Master Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 859    Accepted Submission(s): 325 Problem Description Every school has some legends, Northeastern University is the same. Enter…

odd-even number Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 388    Accepted Submission(s): 212 Problem Description For a number,if the length of continuous odd digits is even and the length…

transaction transaction transaction Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others)Total Submission(s): 1496    Accepted Submission(s): 723 Problem Description Kelukin is a businessman. Every day, he travels arou…

Apple Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 982    Accepted Submission(s): 323 Problem Description Apple is Taotao's favourite fruit. In his backyard, there are three apple trees with…

Clone Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 65536/65536K (Java/Other) Total Submission(s) : 8   Accepted Submission(s) : 5 Font: Times New Roman | Verdana | Georgia Font Size: ← → Problem Description After eating food from Chernobyl,…

2016 ACM ICPC Asia Region - Tehran A - Tax 题目描述:算税. solution 模拟. B - Key Maker 题目描述:给出\(n\)个序列,给定一个序列,问\(n\)个序列中有多少个序列满足对应位的值小于或等于给定序列的值. solution 模拟. C - IOI 2017 Logo 题目描述:有\(m\)件作品,\(n\)个人投票,每个人可以选三件作品,分别给\(1, 2, 3\)分,每件作品按总分排序,总分相同按得\(3\)分的数量排序,还…

ACM ICPC Kharagpur Regional 2017 A - Science Fair 题目描述:给定一个有\(n\)个点,\(m\)条无向边的图,其中某两个点记为\(S, T\),另外标记\(p\)个点表示有一个学生.现在校车从\(S\)出发,接名单上的学生到\(T\),每个学生等概率地出现在名单上,当校车经过某个有学生的点时,不管名单上有没有那位学生,那位学生也会上车.每个学生有一个\(talk\)值,校车完成任务的花费为:到\(T\)时实际学生的\(talk\)值的乘积模\(1…

网络赛:2017 ACM/ICPC Asia Regional Shenyang Online 题目来源:cable cable cable Problem Description: Connecting the display screen and signal sources which produce different color signals by cables, then the display screen can show the color of the signal sou…

transaction transaction transaction Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others)Total Submission(s): 1496    Accepted Submission(s): 723 Problem Description Kelukin is a businessman. Every day, he travels arou…

http://acm.hdu.edu.cn/showproblem.php?pid=4710 Balls Rearrangement Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 735    Accepted Submission(s): 305 Problem Description Bob has N balls and A b…

http://acm.hdu.edu.cn/showproblem.php?pid=4708 Rotation Lock Puzzle Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Problem Description Alice was felling into a cave. She found a strange door with a number square m…

http://acm.hdu.edu.cn/showproblem.php?pid=4715 Difference Between Primes Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Problem Description All you know Goldbach conjecture.That is to say, Every even integer great…

http://acm.hdu.edu.cn/showproblem.php?pid=4712 Hamming Distance Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others) Total Submission(s): 1610    Accepted Submission(s): 630 Problem Description (From wikipedia) For bina…

hduoj 4706 Children's Day 2013 ACM/ICPC Asia Regional Online —— Warmup Herding Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 2005    Accepted Submission(s): 563 Problem Description Little Joh…

http://acm.hdu.edu.cn/showproblem.php?pid=4707 Pet Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Problem Description One day, Lin Ji wake up in the morning and found that his pethamster escaped. He searched in th…

http://acm.hdu.edu.cn/showproblem.php?pid=4706 Children's Day Time Limit: 2000/1000 MS (Java/Others)     Memory Limit: 32768/32768 K (Java/Others) Problem Description Today is Children's Day. Some children ask you to output a big letter 'N'. 'N' is c…

hannnnah_j’s Biological Test Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 802    Accepted Submission(s): 269 Problem Description hannnnah_j is a teacher in WL High school who teaches biolog…