poj 2195Going Home

http://poj.org/problem?id=2195

 #include<cstdio>
 #include<cstring>
 #include<cmath>
 #include<algorithm>
 #include<queue>
 #include<cstdlib>
 #define maxn 500
 using namespace std;
 int n,mm;
 char g[maxn][maxn];
 const int inf=<<;

 struct node
 {
     int x,y;
 }m[maxn];

 struct node1
 {
     int x,y;
 }h[maxn];

 int cap[maxn][maxn];
 int cost[maxn][maxn];
 int flow[maxn][maxn];
 int p[maxn];
 int s,t;
 int main()
 {
     while(scanf("%d%d",&n,&mm)&&n&&mm)
     {
         memset(cap,,sizeof(cap));
         memset(cost,,sizeof(cost));
         int t1=,t2=;
         for(int i=; i<n; i++)
         {
             scanf("%s",g[i]);
             for(int j=; j<mm; j++)
             {
                 if(g[i][j]=='m')
                 {
                     m[++t1].x=i;
                     m[t1].y=j;
                 }
                 else if(g[i][j]=='H')
                 {
                     h[++t2].x=i;
                     h[t2].y=j;
                 }
             }
         }
         for(int i=; i<=t1; i++)
         {
             cap[][i]=;
             cost[][i]=;
         }
         for(int i=; i<=t1; i++)
         {
             for(int j=; j<=t2; j++)
             {
                 cap[i][t1+j]=;
                 cost[i][t1+j]=abs(m[i].x-h[j].x)+abs(m[i].y-h[j].y);
                 cost[t1+j][i]=-cost[i][t1+j];
             }
         }
         for(int j=; j<=t2; j++)
         {
             cap[t1+j][t1+t2+]=;
             cost[t1+j][t1+t2+]=;
         }
         s=,t=t1+t2+;
         queue<int>q;
         int d[maxn];
         memset(flow,,sizeof(flow));
         int c=,f=;
         for(;;)
         {
             bool inq[maxn];
             for(int i=; i<=t1+t2+; i++) d[i]=(i==?:inf);
             memset(inq,,sizeof(inq));
             q.push(s);
             while(!q.empty())
             {
                 int u=q.front();q.pop();
                 inq[u]=false;
                 for(int v=; v<=t1+t2+; v++) if(cap[u][v]>flow[u][v] && d[v]>d[u]+cost[u][v])
                 {
                     d[v]=d[u]+cost[u][v];
                     p[v]=u;
                     if(!inq[v])
                     {
                         inq[v]=true;
                         q.push(v);
                     }
                 }
             }
             if(d[t]==inf) break;
             int a=inf;
             for(int u=t; u!=s; u=p[u])
             {
                 if(cap[p[u]][u]-flow[p[u]][u]<a)
                 {
                     a=cap[p[u]][u]-flow[p[u]][u];
                 }
             }
             for(int u=t; u!=s; u=p[u])
             {
                 flow[p[u]][u]+=a;
                 flow[u][p[u]]-=a;
             }
             c+=d[t]*a;
             f+=a;
         }
         printf("%d\n",c);
     }
     return ;
 }