POJ 2195 Going Home 最小费用最大流 尼玛，心累

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<math.h>
#include<vector>
#include<map>
#include<algorithm>
#include<queue>
using namespace std;
const int maxn=10005;
const int maxm=20505;
const int inf=0x3f3f3f3f;
struct Edge{
   int to;
   int next;
   int cap,flow,cost;
}edge[maxm];
int head[maxn],tot;
int pre[maxn],dis[maxn];
bool vis[maxn];
int n;
char str[500];
struct node{
  int x,y;

}p[maxn],q[maxn];


void init(int nn){
    n=nn;
    tot=0;
    memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int cap,int cost){
   edge[tot].to=v;
   edge[tot].cap=cap;
   edge[tot].cost=cost;
   edge[tot].flow=0;
   edge[tot].next=head[u];
   head[u]=tot++;
    edge[tot].to=u;
   edge[tot].cap=0;
   edge[tot].cost=-cost;
   edge[tot].flow=0;
   edge[tot].next=head[v];
   head[v]=tot++;
}
bool spfa(int s,int t){
      queue<int >q;
//    printf("n====%d\n",n);
    for(int i=0;i<=n;i++){
         dis[i]=inf;
         vis[i]=false;
         pre[i]=-1;
    }
    dis[s]=0;
    vis[s]=true;
    q.push(s);
    while(!q.empty()){
        int u=q.front();
        q.pop();
        vis[u]=false;
        for(int i=head[u];i!=-1;i=edge[i].next){
            int v=edge[i].to;
            if(edge[i].cap>edge[i].flow&&dis[v]>dis[u]+edge[i].cost){
               dis[v]=dis[u]+edge[i].cost;
               pre[v]=i;
               if(!vis[v]){
                  vis[v]=true;
                  q.push(v);
               }

            }
        }


    }
    if(pre[t]==-1)
        return false;
    else
        return true;

}
int mincost(int s,int t,int &cost){
      int flow=0;
      cost=0;
    //  printf("%d\n",head[2]);
      while(spfa(s,t)){
          int Min=inf;
        for(int i=pre[t];i!=-1;i=pre[edge[i^1].to]){
            if(Min>edge[i].cap-edge[i].flow)
                Min=edge[i].cap-edge[i].flow;
        }
        for(int i=pre[t];i!=-1;i=pre[edge[i^1].to]){
                edge[i].flow+=Min;
                edge[i^1].flow-=Min;
                cost+=edge[i].cost*Min;

        }
        flow+=Min;

      }

//      printf("cost=====%d  flow======%d\n",cost,flow);
      return flow;
}

int main(){
     int x,y;
     while(scanf("%d%d",&x,&y)!=EOF){
             if(x==0&&y==0)
                 break;
             n=x*y+1;
             init(n);
             int start=0;
             int end=n;
             int pp=0,qq=0;
             for(int i=1;i<=x;i++){
                   scanf("%s",str+1);
                 for(int j=1;j<=y;j++){
                      int cnt=(i-1)*y+j;
                      if(str[j]==‘m‘){
                         addedge(start,cnt,1,0);
                         p[pp].x=i;
                         p[pp++].y=j;
                      }
                      if(str[j]==‘H‘){
                         addedge(cnt,end,1,0);
                         q[qq].x=i;
                         q[qq++].y=j;
                      }
                }
            //     printf("%s\n",str+1);
             }

             for(int i=0;i<pp;i++){
                 for(int j=0;j<qq;j++){
                     addedge((p[i].x-1)*y+p[i].y,(q[j].x-1)*y+q[j].y,1,abs(p[i].x-q[j].x)+abs(p[i].y-q[j].y));
                 }
             }
         int tmp;
            int ans=mincost(start,end,tmp);
            printf("%d\n",tmp);

     }
     return 0;
}