bzoj1179: [Apio2009]Atm

#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<stack>
#include<queue>
using namespace std;
#define rep(i,s,t) for(int i=s;i<=t;i++)
#define dwn(i,s,t) for(int i=s;i>=t;i--)
#define clr(x,c) memset(x,c,sizeof(x))
#define qwq(x) for(edge *o=head[x];o;o=o->next)
#define qaq(x) for(edge *o=h[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=500005;
const int inf=0x7f7f7f7f;
struct edge{
    int to;edge *next;
};
edge es[nmax<<1],*pt=es,*head[nmax],*h[nmax];
void add(int u,int v){
    pt->to=v;pt->next=head[u];head[u]=pt++;
}
int pre[nmax],a[nmax],scc[nmax],dfs_clock,scc_cnt;
stack<int>s;
int dfs(int x){
    int lowu=pre[x]=++dfs_clock;s.push(x);
    qwq(x){
        if(!pre[o->to]) lowu=min(lowu,dfs(o->to));
        else if(!scc[o->to]) lowu=min(lowu,pre[o->to]);
    }
    if(lowu==pre[x]){
        int o;scc_cnt++;
        while(1){
            o=s.top();s.pop();scc[o]=scc_cnt;
            if(o==x) break;
        }
    }
    return lowu;
}
void adde(int u,int v){
    pt->to=v;pt->next=h[u];h[u]=pt++;
}
int dist[nmax];bool inq[nmax];
queue<int>q;
void spfa(int s){
    q.push(s);inq[s]=1;dist[s]=a[s];
    int tx,td;
    while(!q.empty()){
        tx=q.front();q.pop();inq[tx]=0;
        qaq(tx) if(dist[o->to]<dist[tx]+a[o->to]){
            dist[o->to]=dist[tx]+a[o->to];
            if(!inq[o->to]) q.push(o->to),inq[o->to]=1;
        }
    }
}
int main(){
    int n=read(),m=read(),u,v;
    rep(i,1,m) u=read(),v=read(),add(u,v);
    rep(i,1,n) if(!pre[i]) dfs(i);
    rep(i,1,n) u=read(),a[scc[i]]+=u;
    rep(i,1,n) {
        qwq(i) {
            u=scc[i],v=scc[o->to];
            if(u!=v) adde(u,v);
        }
    }
    int s=read(),tm=read(),ans=0;
    spfa(scc[s]);
    rep(i,1,tm) u=read(),ans=max(ans,dist[scc[u]]);
    printf("%d\n",ans);
    return 0;
}