HDU 3395 Special Fish 最小费用流/KM

http://acm.hdu.edu.cn/showproblem.php?pid=3395

A fish will spawn after it has been attacked. Each fish can attack one other fish and can only be attacked once.用KM,

当时用最小费用最大流的时候老是WA

看了AC神的 blog  http://hi.baidu.com/aekdycoin/blog/item/3bc9df1fa2327d1340341755.html  !!! 以后构图注意了

代码(第一个最大费用最大流):

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#define nMAX 205
#define mMAX 100005
#define inf 1<<28
struct Edge
{
    int u,v,cap,cost,nxt;
}edge[mMAX];
int pre[nMAX],head[nMAX],qu[nMAX],dis[nMAX],val[nMAX];
bool vs[nMAX];
int s_edge,maxf,ans;
void addedge(int u,int v,int ca,int co)
{
    edge[++s_edge].v=v;
    edge[s_edge].cap=ca;
    edge[s_edge].cost=co;
    edge[s_edge].nxt=head[u];
    head[u]=s_edge;

    edge[++s_edge].v=u;
    edge[s_edge].cap=0;
    edge[s_edge].cost=-co;
    edge[s_edge].nxt=head[v];
    head[v]=s_edge;
}

bool spfa(int s,int t,int n)//始点  终点  总点数
{
    int start=0, tail=1;
    for(int i=0;i<=n;i++)
    {
        dis[i]=-inf;//////////////////长注释的地方就是最大费用流要改的地方
        vs[i]=0;
    }
    qu[0]=s;
    vs[s]=1;
    dis[s]=0;
    while(start!=tail)
    {
        int u=qu[start];
        for(int e=head[u];e;e=edge[e].nxt)
        {
           int v=edge[e].v;
           if(edge[e].cap&&dis[v]<dis[u]+edge[e].cost)///////////
           {
               dis[v]=dis[u]+edge[e].cost;
               pre[v]=e;
               if(!vs[v])//放if里面
               {
                   qu[tail++]=v;
                   vs[v]=1;
                   if(tail==nMAX)tail=0;
               }

           }

        }
        vs[u]=0;
        start++;
        if(start==nMAX)start=0;
    }
    if(dis[t]==-inf)return 0;/////////////////////
    return 1;
}
void end(int s,int t)
{
    int p,u;
    for(u=t;u!=s;u=edge[p^1].v)
    {
        p=pre[u];
        edge[p].cap-=1;
        edge[p^1].cap+=1;
        ans+=edge[p].cost;
    }
}
int main()
{
    int i,j,s,t,m,N,p;
    char ch[105];
    while(~scanf("%d",&N))
    {
        if(N==0)break;
        s_edge=1;
        memset(head,0,sizeof(head));
        for(i=1;i<=N;i++)
           scanf("%d",&val[i]);
        for(i=1;i<=N;i++)
        {
            for(j=1;j<=N;j++)
            {
                scanf("%1d",&p);
                if(p)
                {
                    addedge(i,j+N,1,val[i]^val[j]);
                }

            }
        }
    s=0,t=2*N+1;
    for(i=1;i<=N;i++)
    {
       addedge(0,i,1,0);
       addedge(i+N,t,1,0);
       addedge(i,t,1,0);
    }

    ans=0;
    while(spfa(s,t,t))end(s,t);
    printf("%d\n",ans);
    }
    return 0;
}