hdu2426Interesting Housing Problem

http://acm.hdu.edu.cn/showproblem.php?pid=2426

#include <iostream>#include <cstdio>using namespace std;const int oo=1e7;const int mm=111111;const int mn=8888;int node,src,dest,edge,ans;int ver[mm],flow[mm],cost[mm],next[mm];int head[mn],dis[mn],p[mn],q[mn],vis[mn],work[mn];void prepare(int _node,int _src,int _dest){   node=_node,src=_src,dest=_dest;   for(int i=0;i<node;++i)head[i]=-1,vis[i]=0;   edge=0;}void addedge(int u,int v,int f,int c){   ver[edge]=v,flow[edge]=f,cost[edge]=c,next[edge]=head[u],head[u]=edge++;   ver[edge]=u,flow[edge]=0,cost[edge]=-c,next[edge]=head[v],head[v]=edge++;}bool spfa(){    int i,u,v,l,r=0,tmp;    for(i=0;i<node;i++) dis[i]=-oo;    dis[q[r++]=src]=0;    p[src]=p[dest]=-1;    for(l=0;l!=r;(++l>=mn)?l=0:l)        for(i=head[u=q[l]],vis[u]=0;i>=0;i=next[i])            if(flow[i]&&dis[v=ver[i]]<(tmp=dis[u]+cost[i]))            {                dis[v]=tmp;//cout<<"u="<<u<<" v="<<v<<" tmp="<<tmp<<endl;                p[v]=i^1;                if(vis[v])  continue;                vis[q[r++]=v]=1;                if(r>=mn)   r=0;            }    return p[dest]>-1;}int Spfaflow(){    int i,ret=0,delta;    while(spfa())    {        for(i=p[dest],delta=oo;i>=0;i=p[ver[i]])            if(flow[i^1]<delta) delta=flow[i^1];            ans+=delta;        for(i=p[dest];i>=0;i=p[ver[i]])            flow[i]+=delta,flow[i^1]-=delta;        ret+=delta*dis[dest];//cout<<"ret="<<ret<<endl;    }    return ret;}int main(){    int n,m,k,s,r,v,i,cas=0;    while(~scanf("%d%d%d",&n,&m,&k))    {        prepare(n+m+2,0,n+m+1);        if(n>m)        {            printf("Case %d: -1\n",++cas);            continue;        }        for(i=1;i<=n;i++)            addedge(src,i,1,0);        for(i=1;i<=m;i++)            addedge(n+i,dest,1,0);        while(k--)        {            scanf("%d%d%d",&s,&r,&v);            s++;            r++;            if(v>=0)            addedge(s,n+r,oo,v);        }        ans=0;        int kk=Spfaflow();        if(ans==n)        printf("Case %d: %d\n",++cas,kk);        else        printf("Case %d: -1\n",++cas);    }    return 0;}