HDU-5001 Walk （概率DP）

# include<iostream>
# include<cstdio>
# include<vector>
# include<cstring>
# include<algorithm>
using namespace std;
vector<int>v[55];
int n,m,d,vis[10005][55];
double dp[10005][55];
void solve()
{
    for(int i=1;i<=n;++i){
        memset(dp,0,sizeof(dp));
        for(int j=1;j<=n;++j)
            dp[0][j]=1.0/n;
        for(int j=1;j<=d;++j){
            for(int start=1;start<=n;++start){
                if(i==start)
                    continue;
                int l=v[start].size();
                for(int k=0;k<l;++k)
                    dp[j][v[start][k]]+=dp[j-1][start]*1.0/l;
            }
        }
        double ans=0.0;
        for(int j=1;j<=n;++j)
            if(j!=i)
                ans+=dp[d][j];
        printf("%.10lf\n",ans);
    }
}
int main()
{
    int T,a,b;
    vector<int>::iterator it;
    scanf("%d",&T);
    while(T--)
    {
        memset(vis,0,sizeof(vis));
        scanf("%d%d%d",&n,&m,&d);
        for(int i=1;i<=n;++i)
            v[i].clear();
        while(m--)
        {
            scanf("%d%d",&a,&b);
            it=find(v[a].begin(),v[a].end(),b);
            if(it==v[a].end())
                v[a].push_back(b);
            it=find(v[b].begin(),v[b].end(),a);
            if(it==v[b].end())
                v[b].push_back(a);
        }
        solve();
    }
    return 0;
}