【bzoj3171】[Tjoi2013]循环格

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<cmath>
using namespace std;
const int N=15*15*4;
const int M=N*50;
const int inf=0x7fffffff;
int head
,next[M],key[M],w[M],cost[M],tot;
int dist
,inq
,fr
,mn
;queue<int>q;
int S,T;
char map

;
int n,m;
const int dx[]={0,0,-1,1};
const int dy[]={-1,1,0,0};

void add(int x,int y,int z,int c)
{
tot++;next[tot]=head[x];head[x]=tot;key[tot]=y;w[tot]=z;cost[tot]=c;
tot++;next[tot]=head[y];head[y]=tot;key[tot]=x;w[tot]=0;cost[tot]=-c;
}
void bili()
{
tot=-1;
memset(head,-1,sizeof(head));
}
int spfa()
{
for(int i=S;i<=T;i++)dist[i]=inf,mn[i]=inf;
dist[S]=0;
q.push(S);
while(!q.empty())
{
int x=q.front();
q.pop();
inq[x]=0;
for(int i=head[x];i!=-1;i=next[i])
{
int y=key[i];
if(w[i]&&dist[y]>dist[x]+cost[i])
{
dist[y]=dist[x]+cost[i];
fr[y]=i;
mn[y]=min(mn[x],w[i]);
if(inq[y]==0)q.push(y),inq[y]=1;
}
}
}
if(dist[T]==inf)return 0;
return 1;
}
long long zeng()
{
for(int i=T;i!=S;i=key[fr[i]^1])
w[fr[i]]-=mn[T],w[fr[i]^1]+=mn[T];
return (long long)dist[T]*mn[T];
}
int get(int x,int y)
{
if(y>m)y=1;
if(y<1)y=m;
if(x>n)x=1;
if(x<1)x=n;
return (x-1)*m+y;
}
int main()
{
bili();
cin>>n>>m;
S=0,T=n*m*2+1;
for(int i=1;i<=n;i++)scanf("%s",map[i]+1);
for(int i=1;i<=n;i++)
for(int j=1;j<=m;j++)
{
int id=get(i,j);
add(S,id,1,0);
int nx,ny;
if(map[i][j]=='R')nx=i,ny=j+1;
if(map[i][j]=='L')nx=i,ny=j-1;
if(map[i][j]=='U')nx=i-1,ny=j;
if(map[i][j]=='D')nx=i+1,ny=j;
for(int k=0;k<4;k++)
{
int ni=dx[k]+i;
int nj=dy[k]+j;
if(ni==nx&&nj==ny)add(id,get(ni,nj)+n*m,1,0);
else add(id,get(ni,nj)+n*m,1,1);
}
add(id+n*m,T,1,0);
}
int ans=0;
while(spfa())ans+=zeng();
printf("%d\n",ans);
}