bzoj 2561

 1 #include<bits/stdc++.h>
 2 #define inc(i,l,r) for(int i=l;i<=r;i++)
 3 #define dec(i,l,r) for(int i=l;i>=r;i--)
 4 #define link(x) for(edge *j=h[x];j;j=j->next)
 5 #define mem(a) memset(a,0,sizeof(a))
 6 #define inf 1e9
 7 #define ll long long
 8 #define succ(x) (1<<x)
 9 #define nm 800000+5
10 #define NM 20000+5
11 using namespace std;
12 int read(){
13     int x=0,f=1;char ch=getchar();
14     while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
15     while(isdigit(ch))x=x*10+ch-‘0‘,ch=getchar();
16     return x*f;
17 }
18 struct edge{
19     int t,v;
20     edge *next,*rev;
21 }e[nm],*h[NM],*p=e;
22 void _add(int x,int y,int v){
23     p->t=y;p->v=v;p->next=h[x];h[x]=p;p++;
24 }
25 void add(int x,int y,int v){
26     _add(x,y,v);_add(y,x,0);
27     h[x]->rev=h[y];h[y]->rev=h[x];
28 }
29 int n,m,S,T,_t,l[nm],r[nm],dis[nm],d[NM],k,ans;
30 bool v[NM];
31 queue<int >q;
32 int bfs(){
33     mem(v);mem(d);
34     v[S]++;d[S]++;q.push(S);
35     while(!q.empty()){
36         int t=q.front();q.pop();
37         link(t)
38         if(j->v&&(!d[j->t]||d[j->t]>d[t]+1)){
39             d[j->t]=d[t]+1;
40             if(!v[j->t])v[j->t]++,q.push(j->t);
41         }
42     }
43     return d[T];
44 }
45 int dfs(int x,int k){
46     int _a;
47     if(x==T)return k;
48     link(x)
49     if(j->v&&d[j->t]==d[x]+1&&(_a=dfs(j->t,min(j->v,k)))){
50         j->v-=_a;j->rev->v+=_a;return _a;
51     }
52     return 0;
53 }
54 int main(){
55 //    freopen("data.in","r",stdin);
56     n=read();m=read();
57     inc(i,1,m){
58         l[i]=read();r[i]=read();dis[i]=read();
59     }
60     S=read();T=read();k=read();
61     inc(i,1,m)
62     if(dis[i]>k)add(l[i],r[i],1),add(r[i],l[i],1);
63     while(bfs())
64     if(_t=dfs(S,inf))ans+=_t;
65     p=e;mem(h);
66     inc(i,1,m)
67     if(dis[i]<k)add(l[i],r[i],1),add(r[i],l[i],1);
68     while(bfs())
69     if(_t=dfs(S,inf))ans+=_t;
70     printf("%d\n",ans);
71     return 0;
72 }