当前位置：网站首页>poj3744 Scout YYF I

poj3744 Scout YYF I

2022-08-08 13:21:00 【51CTO】


​ ​http://www.elijahqi.win/archives/3628​​​
Description

YYF is a couragous scout. Now he is on a dangerous mission which is to penetrate into the enemy’s base. After overcoming a series difficulties, YYF is now at the start of enemy’s famous “mine road”. This is a very long road, on which there are numbers of mines. At first, YYF is at step one. For each step after that, YYF will walk one step with a probability of p, or jump two step with a probality of 1-p. Here is the task, given the place of each mine, please calculate the probality that YYF can go through the “mine road” safely.
Input

The input contains many test cases ended with EOF.
Each test case contains two lines.
The First line of each test case is N (1 ≤ N ≤ 10) and p (0.25 ≤ p ≤ 0.75) seperated by a single blank, standing for the number of mines and the probability to walk one step.
The Second line of each test case is N integer standing for the place of N mines. Each integer is in the range of [1, 100000000].
Output

For each test case, output the probabilty in a single line with the precision to 7 digits after the decimal point.
Sample Input

1 0.5
2
2 0.5
2 4
Sample Output

0.5000000
0.2500000
Source

POJ Monthly Contest - 2009.08.23, Simon
注意tle可能因为在快速幂的时候出现连续两个雷在一起的情况 特判之即可
剩下就是普通dp+矩阵快速幂而已..

      
      

       
       #include<cstdio>
       
       
#include<cstring>
       
       
#include<algorithm>
       
       
using namespace std;
       
       
struct matrix{
       
       
    double f[4][4];
       
       
}tr,ans;
       
       
inline matrix multiply(const matrix &a,const matrix &b){
       
       
    matrix c;memset(c.f,0,sizeof(c.f));
       
       
    for (int i=1;i<=3;++i)
       
       
        for (int k=1;k<=3;++k)
       
       
            for (int j=1;j<=3;++j)
       
       
                c.f[i][j]+=a.f[i][k]*b.f[k][j];
       
       
    return c;
       
       
}
       
       
int n,ps[11];double p;
       
       
int main(){
       
       
    freopen("poj3744.in","r",stdin);
       
       
    while(~scanf("%d%lf",&n,&p)){
       
       
        for (int i=1;i<=n;++i) scanf("%d",&ps[i]);
       
       
        sort(ps+1,ps+n+1);memset(tr.f,0,sizeof(tr.f));bool flag=1;
       
       
        for (int i=1;i<=n;++i) if (ps[i-1]+1==ps[i]) {puts("0.0000000");flag=0;break;}
       
       
        if(!flag) continue;tr.f[2][1]=1;tr.f[3][2]=1;tr.f[2][3]=1-p;tr.f[3][3]=p;
       
       
        matrix ans;memset(ans.f,0,sizeof(ans.f));ans.f[1][3]=1;int now=1;
       
       
        for (int i=1;i<=n;++i){
       
       
            int t=ps[i]-now-1;matrix b=tr;
       
       
            for (;t;b=multiply(b,b),t>>=1) if (t&1) ans=multiply(ans,b);
       
       
            ans.f[1][1]=ans.f[1][3];ans.f[1][2]=0;ans.f[1][3]=ans.f[1][1]*(1-p);now=ps[i]+1;
       
       
        }printf("%.7f\n",ans.f[1][3]);
       
       
    }
       
       
    return 0;
       
       
}
      
      

      
      
    
       
       
  • 1.
    • 
       
       
  • 2.
    • 
       
       
  • 3.
    • 
       
       
  • 4.
    • 
       
       
  • 5.
    • 
       
       
  • 6.
    • 
       
       
  • 7.
    • 
       
       
  • 8.
    • 
       
       
  • 9.
    • 
       
       
  • 10.
    • 
       
       
  • 11.
    • 
       
       
  • 12.
    • 
       
       
  • 13.
    • 
       
       
  • 14.
    • 
       
       
  • 15.
    • 
       
       
  • 16.
    • 
       
       
  • 17.
    • 
       
       
  • 18.
    • 
       
       
  • 19.
    • 
       
       
  • 20.
    • 
       
       
  • 21.
    • 
       
       
  • 22.
    • 
       
       
  • 23.
    • 
       
       
  • 24.
    • 
       
       
  • 25.
    • 
       
       
  • 26.
    • 
       
       
  • 27.
    • 
       
       
  • 28.
    • 
       
       
  • 29.
    • 
       
       
  • 30.
    • 
       
       
  • 31.
    • 
       
       
  • 32.
    •


原网站

版权声明
本文为[51CTO]所创，转载请带上原文链接，感谢
https://blog.51cto.com/u_15744996/5555033

边栏推荐

猜你喜欢

随机推荐