luogu2754 星际转移问题

源向地球连

月球向汇连

每一天往下一天连

飞船上一天与这一天连

枚举答案

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
struct Edge{
	int too, nxt, val;
}edge[1000005];
int n, m, k, cnt, hea[10005], ans, lev[10005], maxFlow, r[25], l[25];
int a[25][25], ss, tt;
const int oo=0x3f3f3f3f;
queue<int> d;
void add_edge(int fro, int too, int val){
	edge[cnt].nxt = hea[fro];
	edge[cnt].too = too;
	edge[cnt].val = val;
	hea[fro] = cnt++;
}
void addEdge(int fro, int too, int val){
	add_edge(fro, too, val);
	add_edge(too, fro, 0);
}
bool bfs(){
	memset(lev, 0, sizeof(lev));
	d.push(ss);
	lev[ss] = 1;
	while(!d.empty()){
		int x=d.front();
		d.pop();
		for(int i=hea[x]; i!=-1; i=edge[i].nxt){
			int t=edge[i].too;
			if(!lev[t] && edge[i].val>0){
				lev[t] = lev[x] + 1;
				d.push(t);
			}
		}
	}
	return lev[tt]!=0;
}
int dfs(int x, int lim){
	if(x==tt)	return lim;
	int addFlow=0;
	for(int i=hea[x]; i!=-1 && addFlow<lim; i=edge[i].nxt){
		int t=edge[i].too;
		if(lev[t]==lev[x]+1 && edge[i].val>0){
			int tmp=dfs(t, min(lim-addFlow, edge[i].val));
			edge[i].val -= tmp;
			edge[i^1].val += tmp;
			addFlow += tmp;
		}
	}
	return addFlow;
}
void dinic(){
	while(bfs())	maxFlow += dfs(ss, oo);
}
int main(){
	memset(hea, -1, sizeof(hea));
	cin>>n>>m>>k;
	for(int i=1; i<=m; i++){
		scanf("%d %d", &r[i], &l[i]);
		for(int j=0; j<l[i]; j++){
			scanf("%d", &a[i][j]);
			a[i][j] += 2;
		}
	}
	n += 2;
	ss = 0; tt = 9999;
	while(ans<500){
		addEdge(ss, ans*n+2, oo);
		addEdge(ans*n+1, tt, oo);
		if(ans){
			for(int i=1; i<=n; i++)
				addEdge((ans-1)*n+i, ans*n+i, oo);
			for(int i=1; i<=m; i++){
				int uu=a[i][(ans-1)%l[i]];
				int vv=a[i][ans%l[i]];
				addEdge((ans-1)*n+uu, ans*n+vv, r[i]);
			}
		}
		dinic();
		if(maxFlow>=k)	break;
		ans++;
	}
	if(ans<500)	cout<<ans<<endl;
	else	cout<<"0"<<endl;
	return 0;
}