hdu acm 1083 看不懂题意

Consider a group of N students and P courses.
有N个学生，P门课

Each student visits zero,
one or more than one courses.
每一个学生学习一些课程。

Your task is to determine whether it is possible to form a committee of exactly P students that satisfies simultaneously the conditions:
你的任务是判断是否能可能P个学习符合下面的情况。

. every student in the committee represents a different course (a student can represent a course if he/she visits that course)
每一个学生参加不同的课程

. each course has a representative in the committee
每一个课程都有学生参加。

解题报告：因为课程有P个，而且只选择P个学生，每一个学生加参的课程不同，而且每一门课都

有学生参加，这就是说有P个学生和这P门课一一对应，也就是最大二分匹配问题。

#include
#include
int cours[101];
int stu[301];
int adj[101][301];
int m[301];
int p,n;
int DFS(int from)
{
int i;
for(i=1;i<=n;i++)
{
if(adj[from][i]==1&&m[i]==0)
{
m[i]=1;
if(stu[i]==-1||DFS(stu[i]))
{
stu[i]=from;
cours[from]=i;
return 1;
}
}
}
return 0;
}
int main()
{
int i,t,temp,j;
scanf("%d",&t);
while(t--)
{
scanf("%d%d",&p,&n);
memset(cours,-1,sizeof(cours));
memset(stu,-1,sizeof(stu));
memset(adj,0,sizeof(adj));
for(i=1;i<=p;i++)
{
scanf("%d",&temp);
while(temp--)
{
scanf("%d",&j);
adj[i][j]=1;
}
}
for(i=1;i<=p;i++)
{
if(cours[i]==-1)
{
memset(m,0,sizeof(m));
if(DFS(i)==0)
break;
}
}
if(i>p)
printf("YES\n");
else
printf("NO\n");
}
}