C++11(clang++ 3.9) 解法, 执行用时: 5ms, 内存消耗: 604K, 提交时间: 2020-06-06 14:57:09

#include<bits/stdc++.h>

using namespace std;
#define ll long long
#define ls o<<1
#define rs o<<1|1
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define mp make_pair
const double pi=acos(-1.0);
const double eps=1e-10;
const int mod=1e9+7;
const int INF=0x3f3f3f3f;
const int maxn=1005;
int n,tot,s,t,cnt,sum;
struct node{
	int a,b,p1,p2,v;
}buf[maxn];
struct edge{
	int to,nxt,we;
}es[100005];
int head[3005],dep[3005],cur[3005];
queue<int>q;
void init(){
	tot=0;
	memset(head,-1,sizeof(head));
}
void addEdge(int u,int v,int w){
	es[tot].to=v;
	es[tot].we=w;
	es[tot].nxt=head[u];
	head[u]=tot++;
}
void add(int u,int v,int w){
	addEdge(u,v,w);
	addEdge(v,u,0);
}
int bfs(){
	while(!q.empty())q.pop();
	for(int i=0;i<=2*n+1;i++)dep[i]=0,cur[i]=head[i];
	dep[s]=1;
	q.push(s);
	while(!q.empty()){
		int u=q.front();
		q.pop();
		for(int i=head[u];i!=-1;i=es[i].nxt){
			int v=es[i].to;
			if(es[i].we&&!dep[v]){
				dep[v]=dep[u]+1;
				if(v==t)return 1;
				q.push(v);
			}
		}
	}
	return 0;
}
int dfs(int u,int flow){
	int rflow;
	if(u==t)return flow;
	int used=0;
	for(int i=cur[u];i!=-1;i=es[i].nxt){
		cur[u]=i;
		int v=es[i].to;
		if(es[i].we&&dep[v]==dep[u]+1){
			if(rflow=dfs(v,min(es[i].we,flow-used))){
				es[i].we-=rflow;
				es[i^1].we+=rflow;
				used+=rflow;
				if(used==flow)break;
			}
			else dep[v]=0;
		}
	}
	return used;
}
int dinic(){
	int ans=0;
	while(bfs())ans+=dfs(s,INF);
	return ans;
}
int main(void){
//	freopen("in_7.txt","r",stdin);
//	freopen("out_7.txt","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&buf[i].a);
	for(int i=1;i<=n;i++)scanf("%d",&buf[i].b);
	for(int i=3;i<=n;i++){
		scanf("%d%d%d",&buf[i].p1,&buf[i].p2,&buf[i].v);
	}
	init();
	s=0;t=2*n+1;
	for(int i=1;i<=n;i++){
		add(s,i,buf[i].a);
		add(i,t,buf[i].b);
		sum+=buf[i].a+buf[i].b;
	}
	for(int i=3;i<=n;i++){
		add(i,n+i,buf[i].v);
		add(n+i,buf[i].p1,INF);
		add(n+i,buf[i].p2,INF);
	}
	int ans=dinic();
	printf("%d\n",sum-ans);
	return 0;
}

C++14(g++5.4) 解法, 执行用时: 6ms, 内存消耗: 540K, 提交时间: 2020-08-28 16:21:29

#pragma GCC optimize("-Ofast","-funroll-all-loops")
#include<bits/stdc++.h>
//#define int long long
using namespace std;
const int inf=0x3f3f3f3f;
const int N=4e3+10,M=1e6+10;
int n,a[N],b[N],res,s,t,h[N],cnt;
int head[N],nex[M],to[M],w[M],tot=1;
inline void ade(int a,int b,int c){to[++tot]=b; nex[tot]=head[a]; w[tot]=c; head[a]=tot;}
inline void add(int a,int b,int c){ade(a,b,c);	ade(b,a,0);}
inline int bfs(){
	queue<int> q; q.push(s); memset(h,0,sizeof h); h[s]=1;
	while(q.size()){
		int u=q.front();	q.pop();
		for(int i=head[u];i;i=nex[i]) if(!h[to[i]]&&w[i]) h[to[i]]=h[u]+1,q.push(to[i]);
	}
	return h[t];
}
int dfs(int x,int f){
	if(x==t)	return f;	int fl=0;
	for(int i=head[x];i&&f;i=nex[i]){
		if(w[i]&&h[to[i]]==h[x]+1){
			int mi=dfs(to[i],min(w[i],f));
			w[i]-=mi,w[i^1]+=mi,fl+=mi,f-=mi;
		}
	}
	if(!fl)	h[x]=-1;
	return fl;
}
inline int dinic(){
	int res=0;
	while(bfs())	res+=dfs(s,inf);
	return res;
}
signed main(){
	cin>>n; t=N-5; cnt=n;
	for(int i=1;i<=n;i++)	cin>>a[i],add(s,i,a[i]),res+=a[i];
	for(int i=1;i<=n;i++)	cin>>b[i],add(i,t,b[i]),res+=b[i];
	for(int i=3,x,y,val;i<=n;i++)
		cin>>x>>y>>val,++cnt,add(i,cnt,val),add(cnt,x,val),add(cnt,y,val);
	cout<<res-dinic();
	return 0;
}