hdu 3046 最小割

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int MAXN=500000;
const int MAXM=500000;
const int inf=99999999;
struct edge
{
int v,cap,next;
}edge[MAXM];
int head[MAXN],pre[MAXN],cur[MAXN],level[MAXN],gap[MAXN];
int NE;
void init()
{
NE=0;
memset(head,-1,sizeof(head));
}
void add(int u,int v,int cap)
{
edge[NE].v=v;edge[NE].cap=cap;
edge[NE].next=head[u];head[u]=NE++;

edge[NE].v=u;edge[NE].cap=0;
edge[NE].next=head[v];head[v]=NE++;
}
int SAP(int vs,int vt,int NV)
{
memset(pre,-1,sizeof(pre));
memset(level,0,sizeof(level));
memset(gap,0,sizeof(gap));
for(int i=0;i<NV;i++)cur[i]=head[i];
int u=pre[vs]=vs,maxflow=0,aug=-1;
gap[0]=NV;
while(level[vs]<NV){
loop:
for(int &i=cur[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(edge[i].cap&&level[u]==level[v]+1){
aug==-1?aug=edge[i].cap:aug=min(aug,edge[i].cap);
pre[v]=u;
u=v;
if(v==vt){
maxflow+=aug;
for(u=pre[u];v!=vs;v=u,u=pre[u]){
edge[cur[u]].cap-=aug;
edge[cur[u]^1].cap+=aug;
}
aug=-1;
}
goto loop;
}
}
int minlevel=NV;
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(edge[i].cap&&minlevel>level[v]){
cur[u]=i;
minlevel=level[v];
}
}
gap[level[u]]--;
if(gap[level[u]]==0)break;
level[u]=minlevel+1;
gap[level[u]]++;
u=pre[u];
}
return maxflow;
}
int main()
{//freopen("C:\\Users\\Administrator\\Desktop\\input.txt","r",stdin);
int n,m,kase=0,tmp,vs,vt,NV,i,j;
while(scanf("%d%d",&n,&m)!=EOF)
{
int cur=0;
init();
vs=0,vt=n*m+1,NV=vt+1;
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
{
scanf("%d",&tmp);
cur++;
if(i<n) add(cur,cur+m,1),add(cur+m,cur,1);
if(j<m) add(cur,cur+1,1),add(cur+1,cur,1);
if(tmp==2) add(vs,cur,inf),add(cur,vs,inf);
else if(tmp==1) add(cur,vt,inf),add(vt,cur,inf);
}
printf("Case %d:\n",++kase);
printf("%d\n",SAP(vs,vt,NV));
}
}