Birthday Paradox ||生日悖论
2017-07-31 20:58
453 查看
题目来源HPUACM暑期培训:https://vjudge.net/contest/174968#problem/H
Input
Output
Sample Input
Sample Output
先说一下生日悖论的内容,生日悖论(Birthday paradox)是指,如果一个房间里有23个或23个以上的人,那么至少有两个人的生日相同的概率要大于50%。这就意味着在一个典型的标准小学班级(30人)中,存在两人生日相同的可能性更高。对于60或者更多的人,这种概率要大于99%。从引起逻辑矛盾的角度来说生日悖论并不是一种悖论,从这个数学事实与一般直觉相抵触的意义上,它才称得上是一个悖论。大多数人会认为,23人中有2人生日相同的概率应该远远小于50%。
这儿有更清楚的解释:http://wiki.mbalib.com/wiki/%E7%94%9F%E6%97%A5%E6%82%96%E8%AE%BA
懂了生日悖论后题就简单了
计算对立事件即可:
1 - (n-1)/ n - ( n - 2 ) / n ….(n-k)/n
Sometimes some mathematical results are hard to believe. One of the common problems is the birthday paradox. Suppose you are in a party where there are 23 people including you. What is the probability that at least two people in the party have same birthday? Surprisingly the result is more than 0.5. Now here you have to do the opposite. You have given the number of days in a year. Remember that you can be in a different planet, for example, in Mars, a year is 669 days long. You have to find the minimum number of people you have to invite in a party such that the probability of at least two people in the party have same birthday is at least 0.5.
Input
Input starts with an integer T (≤ 20000), denoting the number of test cases. Each case contains an integer n (1 ≤ n ≤ 105) in a single line, denoting the number of days in a year in the planet.
Output
For each case, print the case number and the desired result.
Sample Input
2 365 669
Sample Output
Case 1: 22 Case 2: 30
先说一下生日悖论的内容,生日悖论(Birthday paradox)是指,如果一个房间里有23个或23个以上的人,那么至少有两个人的生日相同的概率要大于50%。这就意味着在一个典型的标准小学班级(30人)中,存在两人生日相同的可能性更高。对于60或者更多的人,这种概率要大于99%。从引起逻辑矛盾的角度来说生日悖论并不是一种悖论,从这个数学事实与一般直觉相抵触的意义上,它才称得上是一个悖论。大多数人会认为,23人中有2人生日相同的概率应该远远小于50%。
这儿有更清楚的解释:http://wiki.mbalib.com/wiki/%E7%94%9F%E6%97%A5%E6%82%96%E8%AE%BA
懂了生日悖论后题就简单了
计算对立事件即可:
1 - (n-1)/ n - ( n - 2 ) / n ….(n-k)/n
#include<cstdio> #include<cmath> #include<cstring> #include<cstdlib> #include<algorithm> #include<iostream> #include<queue> using namespace std; int main() { int N,n,c=1,a; double p,t; scanf("%d",&N); while(N--) { p=1.0; t=0; scanf("%d",&n); a=0; while(t<0.5)//大于0.5既符合题目要求,不再计算 { a++; p*=(n-a)*1.0/n;//计算 t=1-p; } printf("Case %d: %d\n",c++,a); } return 0; }
相关文章推荐
- LightOj 1104 - Birthday Paradox(生日悖论概率)
- LightOJ1104---Birthday Paradox(生日悖论(概率))
- H - Birthday Paradox【生日悖论】
- Light oj 1104 Birthday Paradox 生日悖论-雀巢原理
- LightOJ 1104 - Birthday Paradox【概率】
- 密码学经典之生日悖论与生日攻击【详解】
- LightOJ - 1104 Birthday Paradox [概率]
- H - Birthday Paradox
- 【Codeforces711E】ZS and The Birthday Paradox [数论]
- 生日悖论扩展引申1-c++代码实现及运行实例结果
- 什么是集合的逻辑悖论(Paradox)与集类(Classes)?
- 数学概念——F 概率(经典问题)birthday paradox
- 生日悖论
- Codeforces Round #369 (Div. 2) E. ZS and The Birthday Paradox 数学
- [Codeforces 711E] ZS and The Birthday Paradox (数学+Legendre公式)
- H - Birthday Paradox
- 【28.57%】【codeforces 711E】ZS and The Birthday Paradox
- 生日悖论扩展引申1-c++代码实现及运行实例结果
- Birthday Paradox (概率)
- 我们的生日提醒助手-生日猪(www.birthdaypig.com)