bzoj4820

 

表示高斯消元总写错。。。

注意，概率和期望高斯消元，我们消的时候，取一个fabs最大的就好，别用eps判了，re惨了。。

 

 

#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
const int N=305;
  
int n,m,pos[N];
 
int head[N*N],tot,to[N*N],pre[N*N];
void addedge(int u,int v) {to[++tot]=v;pre[tot]=head[u];head[u]=tot;}
  
  
char s[N];int ch[N*N][2],cnt,dep[N*N],fail[N*N];
inline int idx(char ch) {return ch=='T'? 0:1;}
void get_fail()
{
    queue<int> q;
    if (ch[0][0]) q.push(ch[0][0]);
    if (ch[0][1]) q.push(ch[0][1]);
    while (!q.empty())
    {
        int u=q.front();q.pop();
        for (int i=0;i<=1;i++) 
        if (ch[u][i]==0) ch[u][i]=ch[fail[u]][i];
        else fail[ch[u][i]]=ch[fail[u]][i],q.push(ch[u][i]);        
    }
}
double a[N][N],bin[N];
void jump(int id) 
{
    a[id][n+1]=-bin[m];
    int x=pos[id];
    while (x) 
    {
        for (int i=head[x];i;i=pre[i]) a[to[i]][id]+=bin[m-dep[x]];
        x=fail[x];
    }
}
void gauss(int n)
{
    for (int i=1;i<=n;i++)
    {
        int j=i;
        for (int k=i+1;k<=n;k++) if (fabs(a[k][i])>fabs(a[i][i])) j=k;
        if (i!=j) swap(a[i],a[j]);
         
        double tmp=a[i][i];
        for (j=i;j<=n+1;j++) a[i][j]/=tmp;
         
        for (j=1;j<=n;j++) if (j!=i)
        {
            tmp=a[j][i];
            for (int k=1;k<=n+1;k++) a[j][k]-=a[i][k]*tmp;
        }
    }
}
int main()
{
    scanf("%d%d",&n,&m);
    bin[0]=1;for (int i=1;i<=m;i++) bin[i]=bin[i-1]*0.5;
      
    for (int i=1;i<=n;i++) 
    {
        scanf("%s",s+1);
        int u=0,id;
        for (int j=1;j<=m;j++) 
        {
            id=idx(s[j]);
            if (ch[u][id]==0) ch[u][id]=++cnt;
            u=ch[u][id];dep[u]=j;addedge(u,i);
        }
        pos[i]=u;
    }
    get_fail();
      
    for (int i=1;i<=n;i++) jump(i);
    for (int i=1;i<=n;i++) a[n+1][i]=1.0;
    a[n+1][n+2]=1.0;
    gauss(n+1);
    for (int i=1;i<=n;i++) printf("%.10lf\n",a[i][n+2]);
    return 0;
}