【BZOJ】2929: [Poi1999]洞穴攀行（最大流）

#include <cstdio>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define for1(i,a,n) for(int i=(a);i<=(n);++i)
#define for2(i,a,n) for(int i=(a);i<(n);++i)
#define for3(i,a,n) for(int i=(a);i>=(n);--i)
#define for4(i,a,n) for(int i=(a);i>(n);--i)
#define CC(i,a) memset(i,a,sizeof(i))
#define read(a) a=getint()
#define print(a) printf("%d", a)
#define dbg(x) cout << (#x) << " = " << (x) << endl
#define error(x) (!(x)?puts("error"):0)
#define rdm(x, i) for(int i=ihead[x]; i; i=e[i].next)
inline const int getint() { int r=0, k=1; char c=getchar(); for(; c<‘0‘||c>‘9‘; c=getchar()) if(c==‘-‘) k=-1; for(; c>=‘0‘&&c<=‘9‘; c=getchar()) r=r*10+c-‘0‘; return k*r; }

const int N=415, oo=~0u>>1;
int ihead[N], cnt=1;
struct dat { int next, to, from, cap; }e[N*N*2];
void add(int u, int v, int c) {
	e[++cnt].next=ihead[u]; ihead[u]=cnt; e[cnt].from=u; e[cnt].to=v; e[cnt].cap=c;
	e[++cnt].next=ihead[v]; ihead[v]=cnt; e[cnt].from=v; e[cnt].to=u; e[cnt].cap=0;
}
int p[N], d[N], gap[N], cur[N];
int isap(int s, int t, int n) {
	for1(i, 0, n) p[i]=0, d[i]=0, gap[i]=0, cur[i]=ihead[i];
	gap[0]=n; int ret=0, f, u=s, i;
	while(d[s]<n) {
		for(i=cur[u]; i; i=e[i].next) if(e[i].cap && d[e[i].to]+1==d[u]) break;
		if(i) {
			p[e[i].to]=cur[u]=i; u=e[i].to;
			if(u==t) {
				for(f=oo; u!=s; u=e[p[u]].from) f=min(f, e[p[u]].cap);
				for(u=t; u!=s; u=e[p[u]].from) e[p[u]].cap-=f, e[p[u]^1].cap+=f;
				ret+=f;
			}
		}
		else {
			if(!(--gap[d[u]])) break;
			d[u]=n; cur[u]=ihead[u];
			for(i=ihead[u]; i; i=e[i].next) if(e[i].cap && d[e[i].to]+1<d[u]) d[u]=d[e[i].to]+1;
			++gap[d[u]];
			if(u!=s) u=e[p[u]].from;
		}
	}
	return ret;
}

int n;
int main() {
	read(n);
	for1(i, 1, n-1) {
		int k=getint();
		while(k--) {
			int t=getint();
			if(i==1 || t==n) add(i, t, 1);
			else add(i, t, oo);
		}
	}
	printf("%d\n", isap(1, n, n));
	return 0;
}