题解:
二分图匹配
裸题匈牙利匹配
代码:
#include<cstdio> #include<cstring> #include<cmath> #include<algorithm> using namespace std; const int N=2005; int fi[N],f[N],num,zz[N],n,m,ne[N],match[N],y,x; int dfs(int x) { for (int i=fi[x];i;i=ne[i]) if (!f[zz[i]]) { f[zz[i]]=1; if (!match[zz[i]]||dfs(match[zz[i]])) { match[zz[i]]=x; return 1; } } return 0; } void jb(int x,int y) { ne[++num]=fi[x]; fi[x]=num; zz[num]=y; } int main() { while (~scanf("%d%d",&n,&m)) { memset(fi,0,sizeof fi); memset(match,0,sizeof match); num=0; for (int i=1;i<=n;i++) { scanf("%d",&y); while (y--) { scanf("%d",&x); jb(i,x); } } int ans=0; for (int i=1;i<=n;i++) { memset(f,0,sizeof f); ans+=dfs(i); } printf("%d ",ans); } }