codevs1033 蚯蚓的游戏问题 裸最小费用最大流，注意要拆点

因为蚯蚓走过的路径不能重合，所以把每个点拆成两个点，容量赋为1，保证不会走过相同的点，再加超级源点（程序中为1）和一个辅助点（程序中为2）容量赋为k来控制蚯蚓的数量，最后汇集到一个超级汇点上。做一遍最小费用最大流即可。

 #include<cstdio>
 #include<cstring>
 #include<iostream>
 #include<algorithm>
 using namespace std;
 struct charge{
     int u,v,cost,c,next;
 }f[];
 int n,m,k,num=,cnt=,point[],q[],pre[],dist[];
 bool vis[];
 void insect(int x,int y,int co,int bei)
 {
     f[cnt].u=x;f[cnt].v=y;f[cnt].cost=bei;f[cnt].c=co;
     f[cnt].next=point[x];point[x]=cnt++;
     f[cnt].u=y;f[cnt].v=x;f[cnt].cost=-bei;f[cnt].c=;
     f[cnt].next=point[y];point[y]=cnt++;
 }
 bool spfa(int begin,int end)
 {
     int mp,a,b,head=,tail=;
     memset(q,,sizeof(q));
     memset(pre,0xff,sizeof(pre));
     memset(dist,0x7f,sizeof(dist));
     memset(vis,,sizeof(vis));
     q[]=begin; dist[begin]=; vis[begin]=;
     while (head<=tail)
     {
         a=q[head];
         vis[a]=;
         mp=point[a];
         while (mp>=)
         {
             if (f[mp].c>){
             b=f[mp].v;
             if (dist[b]>dist[a]+f[mp].cost)
             {
                 dist[b]=dist[a]+f[mp].cost;
                 pre[b]=mp;
                 if (!vis[b]){vis[b]=;tail++;q[tail]=b;}
             }
             }
             mp=f[mp].next;
         }
         head++;
     }
     return dist[end]!=;
 }
 int MCMF(int begin,int end)
 {
     int ans=,mp,i,flow,flowsum=;
     while (spfa(begin,end))
     {
         flow=;
         for (i=pre[end];i!=-;i=pre[f[i].u])
          if (f[i].c<flow) flow=f[i].c;
         for (i=pre[end];i!=-;i=pre[f[i].u])
         {
             f[i].c-=flow;
             f[i^].c+=flow;
         }
         ans+=dist[end];
         flowsum+=flow;
     }
     return ans;
 }
 int main()
 {
     scanf("%d %d %d\n",&n,&m,&k);
     int i,a,b,c,j,ff;
     memset(point,0xff,sizeof(point));
     insect(,,k,);
     for (i=;i<=m;++i)
     {
         scanf("%d",&c); num+=;
         insect(,num-,,); insect(num-,num,,-c);
     }
     ff=;
     for (i=;i<=n;++i)
     {
         for (j=;j<=m+i-;++j)
         {
             scanf("%d",&c); num+=;
             if (j>) insect(ff-,num-,,);
             if (j<m+i-) insect(ff,num-,,);
             insect(num-,num,,-c);
             ff+=;
         }
         ff=num+-(m+i-)*;
     }
     for (i=;i<=m+n-;++i)
      insect(num-(m+n-)*+i*,num+,,);
     num++;
     printf("%d\n",-*MCMF(,num));
     return ;
 }