最小费用最大流

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
#include<vector>
using namespace std;
#define N 10000+10
#define INF 0x3f3f3f3f
struct edge{
    int from,to,cap,flow,cost;
    edge(int a,int b,int c,int d,int e){from=a,to=b,c=cap,d=flow,e=cost;}
};
vector<edge>e;vector<int>g[N];
int row,col;char mp[101][101];int m_x[500],m_y[500],h_x[500],h_y[500];int cnt1=0,cnt2=0;
void add_edge(int f,int to,int cap,int flow,int cost ){
    e.push_back(edge(f,to,cap,0,cost));
    e.push_back(edge(to,f,0,0,-cost));
    int m=e.size();
    g[f].push_back(m-2);//正向边 
    g[to].push_back(m-1);//反向边 
} 
int dis[N],vis[N],res[N],pre[N];
bool spfa(int s,int t,int &flow,int &cost){
    memset(dis,0x3f,sizeof(dis));
    memset(vis,0,sizeof(vis));
    memset(res,0x3f,sizeof(res));
    dis[s]=0;queue<int>q;q.push(s);vis[s]=1;
    while(!q.empty()){
        int u=q.front();q.pop();vis[u]=0;
        for(int i=0;i<g[u].size();i++){
            edge &v=e[g[u][i]];
            if(v.cap>v.flow&&dis[v.to]>dis[u]+v.cost){
                dis[v.to]=dis[u]+v.cost;
                pre[v.to]=g[u][i];
                res[v.to]=min(res[u],v.cap-v.flow);
                if(!vis[v.to]) q.push(v.to),vis[v.to]=1;
            }
        }
    }
    if(dis[t]==INF) return false;
    flow+=res[t];cost+=dis[t]*res[t];
    for(int u=t;u!=s;u=e[pre[u]].from){
        e[pre[u]].flow+=res[t];
        e[pre[u]^1].flow-=res[t];
    }
    return true;
}
int mcmf(int s,int t,int &cost){
    int flow=0;cost =0;
    while(spfa(s,t,flow,cost));
    return flow;
}
int main(){
    
    while(~scanf("%d%d",&row,&col),row+col){
        for(int i=0;i<row;i++) scanf("%s",&mp[i]);
        for(int i=0;i<row;i++)
        for(int j=0;j<col;j++)
        {
            if(mp[i][j]=='m'){
                add_edge(row*col+1,i*col+j,1,0,0);
                m_x[cnt1]=i,m_y[cnt1]=j;cnt1++;
            } 
            else if(mp[i][j]=='H'){
                add_edge(i*col+j,row*col+2,1,0,0);
                h_x[cnt2]=i,h_y[cnt2]=j;cnt2++;
            }
        }
        for(int i=0;i<cnt1;i++)
        for(int j=0;j<cnt2;j++){
            add_edge((m_x[i]*col+m_y[j]),(h_x[i]*col+h_y[j]),1,0,abs(m_x[i]-h_x[i])+abs(m_y[i]-h_y[i]));        
        } 
        //cout<<cnt1<<' '<<cnt2<<endl;
        int cost=0;
        mcmf(row*col+1,row*col+2,cost);
        printf("%d\n",cost);
    }
    return 0;
}

 

转载于:https://www.cnblogs.com/vainglory/p/8603827.html