PAT A1047 student list for course (25)

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
const int MAXC=40000;
char cstu[MAXC][6];
int cstunum=0;
struct cour{
vector<int> stuid;
int length;
cour(){
length=0;
}
}course[2510];
int cmp(int a,int b){
return strcmp(cstu[a],cstu[b])<0;
}
int main(){
int n,k,i,coursenum;
char name[6];
scanf("%d%d",&n,&k);
int j,courseid;
for(i=0;i<n;i++){
scanf("%s %d",name,&coursenum);
strcpy(cstu[cstunum++],name);
for(j=0;j<coursenum;j++){
scanf("%d",&courseid);
//strcpy(course[courseid].cstu[course[courseid].length++],name);
course[courseid].stuid.push_back(i);
course[courseid].length++;
}
}
for(i=1;i<=k;i++){
printf("%d %d\n",i,course[i].length);
sort(course[i].stuid.begin(),course[i].stuid.end(),cmp);
for(j=0;j<course[i].length;j++){
printf("%s\n",cstu[course[i].stuid[j]]);
}

}
system("pause");
return 0;
}