BZOJ2150: 部落战争

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cmath>
  4 #include<cstring>
  5 #include<algorithm>
  6 #include<iostream>
  7 #include<vector>
  8 #include<map>
  9 #include<set>
 10 #include<queue>
 11 #include<string>
 12 #define inf 1000000000
 13 #define maxn 100000+5
 14 #define maxm 100000+5
 15 #define eps 1e-10
 16 #define ll long long
 17 #define pa pair<int,int>
 18 #define for0(i,n) for(int i=0;i<=(n);i++)
 19 #define for1(i,n) for(int i=1;i<=(n);i++)
 20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
 21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
 22 #define for4(i,x) for(int i=head[x],y;i;i=e[i].next)
 23 #define mod 1000000007
 24 using namespace std;
 25 inline int read()
 26 {
 27     int x=0,f=1;char ch=getchar();
 28     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 29     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
 30     return x*f;
 31 }
 32 int  n,m,s,t,r,c,ss,tt,maxflow,tot=1,head[maxn],cur[maxn],h[maxn],in[maxn],num[100][100][2];
 33 queue<int>q;
 34 bool a[100][100];
 35 struct edge{int go,next,v;}e[maxm];
 36 inline void ins(int x,int y,int v)
 37 {
 38     e[++tot]=(edge){y,head[x],v};head[x]=tot;
 39     e[++tot]=(edge){x,head[y],0};head[y]=tot;
 40 }
 41 inline void insert(int x,int y,int l,int r)
 42 {
 43     in[y]+=l;in[x]-=l;ins(x,y,r-l);
 44 }
 45 void build()
 46 {
 47     for0(i,tt)if(in[i]>0)ins(ss,i,in[i]);else if(in[i]<0)ins(i,tt,-in[i]);
 48 }
 49 bool bfs()
 50 {
 51     for(int i=0;i<=tt;i++)h[i]=-1;
 52     q.push(s);h[s]=0;
 53     while(!q.empty())
 54     {
 55         int x=q.front();q.pop();
 56         for(int i=head[x];i;i=e[i].next)
 57          if(e[i].v&&h[e[i].go]==-1)
 58          {
 59             h[e[i].go]=h[x]+1;q.push(e[i].go);
 60          }
 61     }
 62     return h[t]!=-1;
 63 }
 64 int dfs(int x,int f)
 65 {
 66     if(x==t) return f;
 67     int tmp,used=0;
 68     for(int i=cur[x];i;i=e[i].next)
 69      if(e[i].v&&h[e[i].go]==h[x]+1)
 70     {
 71         tmp=dfs(e[i].go,min(e[i].v,f-used));
 72         e[i].v-=tmp;if(e[i].v)cur[x]=i;
 73         e[i^1].v+=tmp;used+=tmp;
 74         if(used==f)return f;       
 75     }
 76     if(!used) h[x]=-1;
 77     return used;
 78 }
 79 void dinic()
 80 {
 81     maxflow=0;
 82     while(bfs())
 83     {
 84         for (int i=0;i<=tt;i++)cur[i]=head[i];maxflow+=dfs(s,inf);
 85     }
 86 }
 87 int minflow()
 88 {
 89     s=ss;t=tt;
 90     dinic();
 91     int ans=e[tot].v;
 92     e[tot].v=e[tot^1].v=0;
 93     s=2*n*m+1;t=0;
 94     dinic();
 95     return ans-maxflow;
 96 }
 97 int main()
 98 {
 99     freopen("input.txt","r",stdin);
100     freopen("output.txt","w",stdout);
101     n=read();m=read();r=read();c=read();
102     for1(i,n)for1(j,m)
103     {
104       char ch=getchar();while(ch!=‘.‘&&ch!=‘x‘)ch=getchar();
105       a[i][j]=ch==‘.‘;
106     }
107     for1(i,n)for1(j,m)num[i][j][0]=num[i][j][1]=(i-1)*m+j,num[i][j][1]+=n*m;
108     s=0;t=2*n*m+1;ss=t+1;tt=t+2;
109     for1(i,n)for1(j,m)if(a[i][j])
110     {
111         insert(s,num[i][j][0],0,1);
112         insert(num[i][j][1],t,0,1);
113         insert(num[i][j][0],num[i][j][1],1,1);
114         int x,y;
115         x=i+r;y=j+c;
116         if(x>0&&x<=n&&y>0&&y<=m&&a[i][j])insert(num[i][j][1],num[x][y][0],0,1);
117         x=i+r;y=j-c;
118         if(x>0&&x<=n&&y>0&&y<=m&&a[i][j])insert(num[i][j][1],num[x][y][0],0,1);
119         x=i+c;y=j+r;
120         if(x>0&&x<=n&&y>0&&y<=m&&a[i][j])insert(num[i][j][1],num[x][y][0],0,1);
121         x=i+c;y=j-r;
122         if(x>0&&x<=n&&y>0&&y<=m&&a[i][j])insert(num[i][j][1],num[x][y][0],0,1);
123     }
124     build();
125     insert(t,s,0,inf);
126     printf("%d\n",minflow());    
127     return 0;
128 }