挺裸的一道最小割

 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 10000+5
10 #define nm 100000
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],*o=e,*p[NM],*tmp[NM];
22 void _add(int x,int y,int v){
23     o->t=y;o->v=v;o->next=h[x];h[x]=o;o++;
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,tot,d[NM],b[105][105],_x,cnt[NM];
30 const int dir[4][2]={0,1,0,-1,-1,0,1,0};
31 bool check(int x,int y){
32     return x&&x<=n&&y&&y<=m;
33 }
34 int maxflow(){
35     int flow=0;edge *j;
36     inc(i,1,n)tmp[i]=h[i];
37     cnt[0]=tot;
38     for(int x=0,s=inf;d[x]<tot;){
39         for(j=tmp[x];j;j=j->next)
40         if(j->v&&d[j->t]+1==d[x])break;
41         if(j){
42             s=min(s,j->v);tmp[x]=p[j->t]=j;
43             if((x=j->t)==n){
44                 for(;x;x=p[x]->rev->t){
45                     p[x]->v-=s;
46                     p[x]->rev->v+=s;
47                 }
48                 flow+=s;s=inf;
49             }
50         }else{
51             if(!--cnt[d[x]])break;
52             d[x]=tot;
53             link(x)
54             if(j->v&&d[j->t]+1<d[x]){
55                 d[x]=d[j->t]+1;
56                 tmp[x]=j;
57             }
58             cnt[d[x]]++;
59             if(x)x=p[x]->rev->t;
60         }
61     }
62     return flow;
63 }
64 int main(){
65 //    freopen("data.in","r",stdin);
66     n=read();m=read();
67     inc(i,1,n)
68     inc(j,1,m)b[i][j]=++tot;
69     tot++;
70     inc(i,1,n)
71     inc(j,1,m){
72         _x=read();
73         if(_x==1)add(0,b[i][j],inf);
74         if(_x==2)add(b[i][j],tot,inf);
75         inc(k,0,3)
76         if(check(i+dir[k][0],j+dir[k][1]))
77         add(b[i][j],b[i+dir[k][0]][j+dir[k][1]],1);
78     }
79     n=tot;tot++;
80     printf("%d\n",maxflow());
81     return 0;
82 }
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posted on 2016-01-02 23:31  onlyRP  阅读(171)  评论(0编辑  收藏  举报