洛谷 [P2763]试题库问题

非常舒适的最大流

非常显然的建图方法,然而因为数组开小卡了很长时间

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
using namespace std;
const int MAXN=2500,MAXM=100005;
int head[MAXN],dep[MAXN],maxflow,nume,s,term,n,k,m,cur[MAXN];
struct edge{
	int to,nxt,cap,flow;
}e[MAXM];
void adde(int from,int to,int cap){
	e[++nume].to=to;
	e[nume].cap=cap;
	e[nume].nxt=head[from];
	head[from]=nume;
}
bool bfs(){
	queue<int> q;
	memset(dep,0,sizeof(dep));
	q.push(s);dep[s]=1;
	while(!q.empty()){
		int u=q.front();q.pop();
		for(int i=head[u];i;i=e[i].nxt){
			int v=e[i].to;
			if(!dep[v]&&e[i].flow<e[i].cap){
				dep[v]=dep[u]+1;
				q.push(v);
			}
		}
	}
	return dep[term];
}
int dfs(int u,int flow){
	if(u==term) return flow;
	int tot=0;
	for(int &i=cur[u];i&&tot<flow;i=e[i].nxt){
		int v=e[i].to;
		if(dep[v]==dep[u]+1&&e[i].flow<e[i].cap){
			if(int t=dfs(v,min(flow-tot,e[i].cap-e[i].flow))){
				e[i].flow+=t;
				e[((i-1)^1)+1].flow-=t;
				tot+=t;
			}
		}
	}
	return tot;
}
void dinic(){
	while(bfs()){
		for(int i=s;i<=term;i++) cur[i]=head[i];
		maxflow+=dfs(s,0x3f3f3f3f);
	}
}
int main(){
	cin>>k>>n;
	s=0,term=n+k+1;
	for(int i=1;i<=k;i++){
		int t;
		scanf("%d",&t);
		m+=t;
		adde(s,i,t);adde(i,s,0);
	}
	for(int i=1;i<=n;i++){
		int t;
		scanf("%d",&t);
		for(int j=1;j<=t;j++){
			int ttt;
			scanf("%d",&ttt);
			adde(ttt,i+k,1);adde(i+k,ttt,0);
		}
		adde(i+k,term,1);adde(term,i+k,0);
	}
	dinic();
	//printf("%d %d
",m,maxflow);
	if(m!=maxflow){
		printf("No Solution!
");
	}else {
		for(int i=1;i<=k;i++){
			printf("%d: ",i);
			for(int j=head[i];j;j=e[j].nxt){
				if((e[j].flow)&&e[j].to!=s) printf("%d ",e[j].to-k);
			}
			printf("
");
		}
	}
}