BZOJ 1066 Dinic

思路:
网络流 建边比较麻烦

//By SiriusRen
#include <queue>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define N 100050
int r,c,d,n=66666,tmp;
char a[105][105],b[105][105];
struct Dinic{
    int first[N],next[N],v[N],w[N],tot,vis[N];
    void add(int x,int y,int z){Add(x,y,z),Add(y,x,0);}
    void Add(int x,int y,int z){w[tot]=z,v[tot]=y,next[tot]=first[x],first[x]=tot++;}
    void init(){
        memset(first,-1,sizeof(first));
        for(int i=1;i<=r;i++)
            for(int j=1;j<=c;j++){
                if(b[i][j]=='L')add(0,(i*c+j)*2,1),tmp++;
                if(a[i][j]!='0')add((i*c+j)*2,(i*c+j)*2+1,a[i][j]-'0');
            }
        for(int i=1;i<=r;i++)
            for(int j=1;j<=c;j++){
                if(a[i][j]=='0')continue;
                for(int k=1;k<=r;k++)
                    for(int l=1;l<=c;l++){
                        if(a[k][l]=='0'||(i==k&&j==l))continue;
                        if((i-k)*(i-k)+(j-l)*(j-l)<=d*d)
                            add((i*c+j)*2+1,(k*c+l)*2,0x3fffff);
                    }
            }
        for(int i=1;i<=r;i++){
            for(int j=1;j<=c;j++){
                if((i-1<d||j-1<d||r-i<d||c-j<d)&&a[i][j]!='0')add((i*c+j)*2+1,n,0x3fffff);
            }
        }
        flow();
    }
    bool tell(){
        queue<int>q;q.push(0);
        memset(vis,-1,sizeof(vis));vis[0]=0;
        while(!q.empty()){
            int t=q.front();q.pop();
            for(int i=first[t];~i;i=next[i])
                if(vis[v[i]]==-1&&w[i])
                    q.push(v[i]),vis[v[i]]=vis[t]+1;
        }
        return vis[n]!=-1;
    }
    int zeng(int x,int y){
        if(x==n)return y;
        int r=0;
        for(int i=first[x];y>r&&~i;i=next[i])
            if(w[i]&&vis[v[i]]==vis[x]+1){
                int t=zeng(v[i],min(y-r,w[i]));
                w[i]-=t,w[i^1]+=t,r+=t;
            }
        if(!r)vis[x]=-1;
        return r;
    }
    void flow(){
        int ans=0,jy;
        while(tell())while(jy=zeng(0,0x3ffffff))ans+=jy;
        printf("%d\n",tmp-ans);
    }
}dinic;
int main(){
    scanf("%d%d%d",&r,&c,&d);
    for(int i=1;i<=r;i++)scanf("%s",a[i]+1);
    for(int i=1;i<=r;i++)scanf("%s",b[i]+1);
    dinic.init();
}

这里写图片描述

posted @ 2016-12-09 20:59  SiriusRen  阅读(89)  评论(0编辑  收藏