BZOJ 1066 蜥蜴(网络流)

很普通的拆点网络流，把每个柱子拆成两个点(i,j,0)和(i,j,1).对于柱子的高度限制则加边((i,j,0),(i,j,1),height).

两个柱子能互相到达则加边((i,j,1),(i1,j1,0),INF). 能到达边界的柱子加边((i,j,1),t,INF).有蜥蜴的柱子加边(s,(i,j,0),1).

跑一遍最大流，答案就是总蜥蜴数-最大流。

# include <cstdio>
# include <cstring>
# include <cstdlib>
# include <iostream>
# include <vector>
# include <queue>
# include <stack>
# include <map>
# include <set>
# include <cmath>
# include <algorithm>
using namespace std;
# define lowbit(x) ((x)&(-x))
# define pi acos(-1.0)
# define eps 1e-
# define MOD
# define INF
# define mem(a,b) memset(a,b,sizeof(a))
# define FOR(i,a,n) for(int i=a; i<=n; ++i)
# define FO(i,a,n) for(int i=a; i<n; ++i)
# define bug puts("H");
# define lch p<<,l,mid
# define rch p<<|,mid+,r
# define mp make_pair
# define pb push_back
typedef pair<int,int> PII;
typedef vector<int> VI;
# pragma comment(linker, "/STACK:1024000000,1024000000")
typedef long long LL;
int Scan() {
    int res=, flag=;
    char ch;
    if((ch=getchar())=='-') flag=;
    else if(ch>=''&&ch<='') res=ch-'';
    while((ch=getchar())>=''&&ch<='')  res=res*+(ch-'');
    return flag?-res:res;
}
void Out(int a) {
    if(a<) {putchar('-'); a=-a;}
    if(a>=) Out(a/);
    putchar(a%+'');
}
const int N=;
//Code begin...

struct Edge{int p, next, w;}edge[];
int head[], cnt=, s, t, vis[];
char s1[][], s2[][];
queue<int>Q;

void add_edge(int u, int v, int w)
{
    edge[cnt].p=v; edge[cnt].next=head[u]; edge[cnt].w=w; head[u]=cnt++;
    edge[cnt].p=u; edge[cnt].next=head[v]; edge[cnt].w=; head[v]=cnt++;
}
int bfs(void)
{
    int i, v;
    mem(vis,-);
    while (!Q.empty()) Q.pop();
    vis[s]=; Q.push(s);
    while (!Q.empty()) {
        v=Q.front(); Q.pop();
        for (i=head[v]; i; i=edge[i].next) {
            if (edge[i].w> && vis[edge[i].p]==-) {
                vis[edge[i].p]=vis[v] + ;
                Q.push(edge[i].p);
            }
        }
    }
    return vis[t]!=-;
}
int dfs(int x, int low)
{
    int i, a, temp=low;
    if (x==t) return low;
    for (i=head[x]; i; i=edge[i].next) {
        if (edge[i].w> && vis[edge[i].p] == vis[x] + ){
            a=dfs(edge[i].p,min(edge[i].w,temp));
            temp-=a; edge[i].w-=a; edge[i^].w += a;
            if (temp==) break;
        }
    }
    if (temp==low) vis[x]=-;
    return low-temp;
}
int main ()
{
    int n, m, d, sum=;
    scanf("%d%d%d",&n,&m,&d);
    FO(i,,n) scanf("%s",s1[i]+);
    FO(i,,n) scanf("%s",s2[i]+);
    s=, t=*n*m+;
    FO(i,,n) FOR(j,,m) {
        if (s1[i][j]!='') add_edge(i*m+j,i*m+j+n*m,s1[i][j]-'');
        if (s2[i][j]=='L') add_edge(s,i*m+j,), ++sum;
        if (i<d||(n--i)<d||j<=d||(m-j+)<=d) add_edge(i*m+j+n*m,t,INF);
        FO(k,,n) FOR(l,,m) {
            if (k==i&&l==j) continue;
            if (abs(k-i)+abs(l-j)<=d) add_edge(i*m+j+n*m,k*m+l,INF);
        }
    }
    int res=, temp;
    while (bfs()) while (temp=dfs(s,INF)) res+=temp;
    printf("%d\n",sum-res);
    return ;
}