bzoj1927: [Sdoi2010]星际竞速

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
#define rep(i,n) for(int i=1;i<=n;i++)
#define clr(x,c) memset(x,c,sizeof(x))
#define op() clr(head,0);pt=edges;
#define qwq(x) for(edge *o=head[x];o;o=o->next)
int read(){
	int x=0;char c=getchar();
	while(!isdigit(c)) c=getchar();
	while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
	return x;
}
const int nmax=1605;
const int maxn=100000;
const int inf=0x7f7f7f7f;
struct edge{
	int to,cap,cost;edge *next,*rev;
};
edge edges[maxn],*pt,*head[nmax],*p[nmax];
int d[nmax],a[nmax];bool inq[nmax];
queue<int>q;
void add(int u,int v,int d,int w){
	pt->to=v;pt->cap=d;pt->cost=w;pt->next=head[u];head[u]=pt++;
}
void adde(int u,int v,int d,int w){
	add(u,v,d,w);add(v,u,0,-w);head[u]->rev=head[v];head[v]->rev=head[u];
}
int mincost(int s,int t){
	int cost=0;
	while(1){
		clr(d,0x7f);d[s]=0;clr(inq,0);inq[s]=1;q.push(s);a[s]=inf;
		while(!q.empty()){
			int x=q.front();q.pop();inq[x]=0;
			qwq(x) if(d[o->to]>d[x]+o->cost&&o->cap>0){
				int to=o->to;d[to]=d[x]+o->cost;
				a[to]=min(a[x],o->cap);p[to]=o;
				if(!inq[to]) q.push(to),inq[to]=1;
			}
		}
		if(d[t]==inf) break;
		cost+=d[t]*a[t];
		int x=t;
		while(x!=s) p[x]->cap-=a[t],p[x]->rev->cap+=a[t],x=p[x]->rev->to;
	}
	return cost;
}
int main(){
	op();
	int n=read(),m=read(),tmp,u,v,w,s=0,t=n+n+1;
	rep(i,n) tmp=read(),adde(s,n+i,1,tmp),adde(s,i,1,0),adde(n+i,t,1,0);
	rep(i,m){
		u=read(),v=read(),w=read();
		u>v?adde(v,u+n,1,w):adde(u,v+n,1,w);
	}
	printf("%d\n",mincost(s,t));
	return 0;
}