BZOJ2561【最小割】

/* I will wait for you */ #include<cstdio>#include<cstdlib>#include<cstring>#include<cmath>#include<ctime>#include<algorithm>#include<iostream>#include<fstream>#include<vector>#include<queue>#include<deque>#include<set>#include<map>#include<string>#define make(a,b) make_pair(a,b)#define fi first#define se second using namespace std; typedef long long LL;typedef unsigned long long ULL;typedef pair<int,int> PII; const int maxn=400010;const int maxm=1000010;const int maxs=26;const int INF=1<<29;const int P=1000000007;const double error=1e-9; struct Edge{ int u,v,w; }E[maxn];struct edge{ int v,a,next; }e[maxm]; int s,t,w,ans,cnt,head[maxn],dis[maxn],cur[maxn],q[maxn],c[maxn]; bool cmp(Edge a,Edge b){    return a.w<b.w;} void insert(int u,int v,int a){    e[cnt]=(edge){v,a,head[u]},head[u]=cnt++;    e[cnt]=(edge){u,a,head[v]},head[v]=cnt++;} int bfs(){    memset(dis,-1,sizeof(dis));    int he=0,ta=1;q[0]=s,dis[s]=0;         while(he!=ta)    {        int u=q[he++];        for(int i=head[u],v;i!=-1;i=e[i].next)            if(e[i].a&&dis[v=e[i].v]==-1) dis[v]=dis[u]+1,q[ta++]=v;    }    return dis[t]!=-1;} int dfs(int u,int a){    if(u==t) return a;    int f,flow=0;    for(int i=cur[u],v;a&&i!=-1;i=e[i].next)    {        if(e[i].a&&dis[v=e[i].v]==dis[u]+1&&(f=dfs(v,min(a,e[i].a)))>0)        {            e[i].a-=f,e[i^1].a+=f,a-=f,flow+=f;            if(e[i].a) cur[u]=i;        }    }    if(!flow) dis[u]=-1;    return flow;} void dinic(){    while(bfs()) memcpy(cur,head,sizeof(cur)),ans+=dfs(s,INF);}     int main(){    int n,m;scanf("%d%d",&n,&m);     for(int i=1;i<=m;i++) scanf("%d%d%d",&E[i].u,&E[i].v,&E[i].w);    sort(E+1,E+m+1,cmp);         scanf("%d%d%d",&s,&t,&w);         memset(head,-1,sizeof(head)),cnt=0;    for(int i=1;i<=m&&E[i].w<w;i++) insert(E[i].u,E[i].v,1);    dinic();         memset(head,-1,sizeof(head)),cnt=0;    for(int i=m;i>=1&&E[i].w>w;i--) insert(E[i].u,E[i].v,1);    dinic();         printf("%d\n",ans);    return 0;}