bzoj3931: [CQOI2015]网络吞吐量

#include<cstdio>
#include<cstring>
#include<iostream>
#include<queue>
#include<algorithm>
using namespace std;
#define rep(i,n) for(int i=1;i<=n;i++)
#define ll long long
#define clr(x,c) memset(x,c,sizeof(x))
#define qwq(x) for(Edge *o=h[x];o;o=o->next)
#define QWQ(x) for(edge *o=head[x];o;o=o->next)
#define REP(i,s,t) for(int i=s;i<=t;i++)
int read(){
	int x=0;char c=getchar();bool f=true;
	while(!isdigit(c)) {
		if(c==‘-‘) f=false; c=getchar();
	}
	while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
	return f?x:-x;
} 
const int nmax=1005;
const int maxn=400005;
const ll inf=(ll)1<<60;
struct edge{
	int to;ll cap;edge *next,*rev;
};
edge edges[maxn],*pt=edges,*head[nmax],*p[nmax],*cur[nmax];
void add(int u,int v,ll w){
	pt->to=v;pt->cap=w;pt->next=head[u];head[u]=pt++;
}
void adde(int u,int v,ll w){
	add(u,v,w);add(v,u,0);head[u]->rev=head[v];head[v]->rev=head[u];
}
struct Edge{
	int to;ll dist;Edge *next;
};
Edge Edges[maxn],*e=Edges,*h[nmax];
void addedge(int u,int v,ll w){
	e->to=v;e->dist=w;e->next=h[u];h[u]=e++;
}
int cnt[nmax],H[nmax];bool inq[nmax];
ll d[nmax];
void spfa(int s,int t,int n){
	rep(i,n) d[i]=inf;
	clr(inq,0);inq[s]=1;d[s]=0;
	queue<int>q;q.push(s);
	while(!q.empty()){
		int x=q.front();q.pop();inq[x]=0;
		qwq(x) if(d[o->to]>d[x]+o->dist){
			d[o->to]=d[x]+o->dist;
			if(!inq[o->to]) q.push(o->to),inq[o->to]=1;
		}
	}
}
ll maxflow(int s,int t,int n){
	clr(cnt,0);cnt[0]=n;clr(H,0);
	ll flow=0,a=inf;int x=s;edge *e;
	while(H[s]<n){
		for(e=cur[x];e;e=e->next) if(e->cap>0&&H[x]==H[e->to]+1) break;
		if(e){
			p[e->to]=cur[x]=e;a=min(a,e->cap);x=e->to;
			if(x==t){
				while(x!=s) p[x]->cap-=a,p[x]->rev->cap+=a,x=p[x]->rev->to;
				flow+=a,a=inf;
			}
		}else{
			if(!--cnt[H[x]]) break;
			H[x]=n;
			for(e=head[x];e;e=e->next) 
			  if(e->cap>0&&H[x]>H[e->to]+1) H[x]=H[e->to]+1,cur[x]=e;
			cnt[H[x]]++;
			if(x!=s) x=p[x]->rev->to;
		}
	}
	return flow;
}
int main(){
	int n=read(),m=read(),u,v;ll w;
	rep(i,m) u=read(),v=read(),w=read(),addedge(u,v,w),addedge(v,u,w);
	/*rep(i,n){
		qwq(i) printf("%d ",o->to);printf("\n");
	}*/
	spfa(1,n,n);
	//rep(i,n) printf("%d ",d[i]);
	rep(i,n) qwq(i) if(d[o->to]==d[i]+o->dist) 
	   if(i==1||i==n) adde(i,o->to,inf);
	   else adde(i+n,o->to,inf);
	/*rep(i,n){
		QWQ(i) printf("%d ",o->to);printf("\n");
	}*/
	rep(i,n) {
		w=read();
		if(i!=1&&i!=n) adde(i,i+n,w);
	}
	printf("%lld\n",maxflow(1,n,n+n-2));
	return 0;
}