[bzoj3955] [WF2013]Surely You Congest

　　首先最短路长度不同的人肯定不会冲突。

　　对于最短路长度相同的人，跑个最大流就行了。。当然只有一个人就不用跑了

　　看起来会T得很惨。。但dinic在单位网络里是O(m*n^0.5)的...

 #include<cstdio>
 #include<iostream>
 #include<cstring>
 #include<algorithm>
 #include<queue>
 using namespace std;
 const int maxn=,inf=;
 struct zs2{
     int too,pre,dis;
 }e1[];int tot1,last1[maxn];
 struct zs1{int dis,id;};
 priority_queue<zs1>q;
 bool u[maxn];
 int dis1[maxn];
 struct zs{
     int too,pre;bool flow;
 }e[];int tot,last[maxn];
 int dl[maxn];
 short dis[maxn];
 int pos[];
 int i,j,k,n,m,ans,s,t,tt,c;

 int ra;char rx;
 inline int read(){
     rx=getchar(),ra=;
     while(rx<''||rx>'')rx=getchar();
     while(rx>=''&&rx<='')ra*=,ra+=rx-,rx=getchar();return ra;
 }

 bool operator <(zs1 a,zs1 b){return a.dis>b.dis;}
 inline void spfa(){
     int i,now;
     memset(dis1,,(n+)<<),dis1[]=,q.push((zs1){,});
     while(!q.empty()){
         while(!q.empty()&&u[q.top().id])q.pop();
         if(q.empty())return;
         now=q.top().id,q.pop(),
         u[now]=;
         for(i=last1[now];i;i=e1[i].pre)if(dis1[e1[i].too]>dis1[now]+e1[i].dis)
             dis1[e1[i].too]=dis1[now]+e1[i].dis,q.push((zs1){dis1[e1[i].too],e1[i].too});
     }
 }
 inline void insert1(int a,int b,int c){
     e1[++tot1].too=b,e1[tot1].dis=c,e1[tot1].pre=last1[a],last1[a]=tot1,
     e1[++tot1].too=a,e1[tot1].dis=c,e1[tot1].pre=last1[b],last1[b]=tot1;
 }
 bool bfs(){
     memset(dis,,(n+)<<);
     int l=,r=,i,now;dl[]=s,dis[s]=;
     while(l<r&&!dis[t])
         for(i=last[now=dl[++l]];i;i=e[i].pre)if(e[i].flow&&!dis[e[i].too])
             dis[e[i].too]=dis[now]+,dl[++r]=e[i].too;
 //  for(i=1;i<=n;i++)printf("0->%d  %d\n",i,dis[i]);
     return dis[t];
 }
 int dfs(int x,int mx){
     if(x==t)return mx;
     int used=,i;bool w;
     for(i=last[x];i;i=e[i].pre)if(e[i].flow&&dis[e[i].too]==dis[x]+){
         w=dfs(e[i].too,);if(w){
             e[i].flow=,e[i^].flow=,used++;
             if(used==mx)return mx;
         }
     }
     dis[x]=;return used;
 }
 inline void insert(int a,int b,int c){//printf("  %d-->%d  %d\n",a,b,c);
     e[++tot].too=b,e[tot].flow=c,e[tot].pre=last[a],last[a]=tot;
     e[++tot].too=a,e[tot].flow=,e[tot].pre=last[b],last[b]=tot;
 }
 inline int check(int L,int R){//printf("check:  %d--%d\n",L,R);
     register int i;int flow=,j;
     for(i=;i<=tt;i+=)e[i].flow=,e[i^].flow=;
     for(j=;i<=tot;i+=,j++)
         e[i].flow=j>=L&&j<=R,e[i^].flow=;
     while(bfs())flow+=dfs(s,inf);
 //  printf("flow:  %d\n",flow);
     return flow;
 }
 bool cmp(int a,int b){return dis1[a]<dis1[b];}
 int main(){
     n=read(),m=read(),c=read();
     for(i=;i<=m;i++)j=read(),k=read(),insert1(j,k,read());
     for(i=;i<=c;i++)pos[i]=read();
     spfa();
 //  for(i=1;i<=n;i++)printf("1-->%d %d\n",i,dis1[i]);
     s=,t=,tot=;
     for(i=;i<=n;i++)for(j=last1[i];j;j=e1[j].pre)
         if(dis1[e1[j].too]==dis1[i]+e1[j].dis)insert(e1[j].too,i,);tt=tot;
     sort(pos+,pos++c,cmp);

     for(i=;i<=c;i++)insert(s,pos[i],);
     int pre;
     for(i=;i<=c&&pos[i]==;i++,ans++);
     for(pre=i;i<=c;i++)if(dis1[pos[i]]!=dis1[pos[i+]]||i==c){
         if(pre==i)ans++;else ans+=check(pre,i);
         pre=i+;
     }
     printf("%d\n",ans);
     return ;
 }

dinic好优越啊...