題目：https://www.patest.cn/contests/pat-a-PRactise/1047

代碼：

#include<cstdio>  #include<cstring>  #include<cstdlib> #include<cmath>#include<vector>#include<algorithm>  using namespace std;  vector<int> c[2510];char name[40010][5];bool cmp(int a,int b){   return strcmp(name[a],name[b])<0;}int main()  {   	int n,k,t,cid;	scanf("%d%d",&n,&k);	for(int i=0;i<n;i++){	  scanf("%s %d",name[i],&t);	  for(int j=0;j<t;j++){	    scanf("%d",&cid);		c[cid].push_back(i);	  }	}	for(int i=1;i<=k;i++){		printf("%d %d/n",i,c[i].size());		sort(c[i].begin(),c[i].end(),cmp);		for(int j=0;j<c[i].size();j++){		    printf("%s/n",name[c[i][j]]);		}	}    system("pause");  }