1412: [ZJOI2009]狼和羊的故事

来源：互联网发布：nginx lua 并发异步编辑：程序博客网时间：2024/04/29 04:25
#include<iostream>#include<cstring>#include<cstdio>#define inf 99999999#define T 10001using namespace std;inline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}struct edge{    int to,next,v;}e[200001];const int xx[4]={-1,0,1,0},yy[4]={0,-1,0,1};int n,m,cnt=1,ans,head[10005],h[10005],map[101][101];void insert(int u,int v,int w){    e[++cnt]=(edge){v,head[u],w};    head[u]=cnt;}void ins(int u,int v,int w){    insert(u,v,w);    insert(v,u,0);}bool bfs(){    int q[10005],t=0,w=1;    memset(h,-1,sizeof(h));    q[0]=0;h[0]=0;    while(t<w){        int now=q[t++],i=head[now];        while(i){            if(e[i].v&&h[e[i].to]==-1){                h[e[i].to]=h[now]+1;                q[w++]=e[i].to;            }            i=e[i].next;        }    }    if(h[T]==-1)return false;    else return true;}int dfs(int x,int f){    if(x==T)return f;    int rest,used=0,i=head[x];    while(i){        if(e[i].v&&h[e[i].to]==h[x]+1){            rest=f-used;            rest=dfs(e[i].to,min(e[i].v,rest));            e[i].v-=rest;            e[i^1].v+=rest;            used+=rest;            if(used==f)return f;        }        i=e[i].next;    }    if(!used)h[x]=-1;    return used;}void dinic(){    while(bfs())ans+=dfs(0,inf);}int main(){    n=read();m=read();    for(int i=1;i<=n;i++)        for(int j=1;j<=m;j++)            map[i][j]=read();    for(int i=1;i<=n;i++)          for(int j=1;j<=m;j++){            if(map[i][j]==1) ins(0,(i-1)*m+j,inf);              else if(map[i][j]==2) ins((i-1)*m+j,T,inf);              for(int k=0;k<4;k++){                int nowx=i+xx[k],nowy=j+yy[k];                  if(nowx<1||nowx>n||nowy<1||nowy>m||map[i][j]==2)continue;                  if(map[i][j]!=1||map[nowx][nowy]!=1)                  ins((i-1)*m+j,(nowx-1)*m+nowy,1);              }              }    dinic();    printf("%d",ans);    return 0;}
1 0