#include<iostream>  #include<sstream>        //istringstream 必须包含这个头文件#include<string>  using namespace std;  int main()  {      string str="i an a boy";      istringstream is(str);      string s;      while(is>>s)      {          cout<<s<<endl;      }        } 

#include<iostream>#include<sstream>#include<cstring>#include<cstdio>#include<map>#include<algorithm>using namespace std;char a[1005];int r[105];map<string,int>mp[105];void init(int k){    istringstream str(a);    string tmp;    str>>tmp;    mp[k].clear();    while(str>>tmp)    {        r[k]++;        mp[k][tmp]=1;    }}double get_avep(int k){    istringstream str(a);    string tmp;    str>>tmp;    int i=0,R=0;    double ansn=0.0;    while(str>>tmp)    {        i++;        if(mp[k][tmp]==1)        {            R++;            ansn+=(R*1.0)/i;        }    }    ansn/=r[k]*1.0;    return ansn;}int main(){    int t;    cin>>t;    while(t--)    {   memset(r,0,sizeof(r));        int n,kcas=0;        cin>>n;        getchar();        for(int i=1;i<=n;++i)        {              gets(a);             init(i);         }        double ans=0.0;        for(int i=1;i<=n;++i)        {            gets(a);            ans+=get_avep(i);        }        ans/=n;        cout<<"Case #"<<++kcas<<": ";        printf("%.6lf\n",ans);    }    return 0;}