hdu_3549_Flow Problem(最大流)

题目连接：http://acm.hdu.edu.cn/showproblem.php?pid=3549

题意：求1到n的最大流

题解：模版题，直接上Claris的ISAP，效率是一般dfs的十倍，ORZ Claris!!!

 #include<cstdio>
 #include<algorithm>
 #define F(i,a,b) for(int i=a;i<=b;i++)
 using namespace std;
 const int N=,inf=~0U>>,M=;
 struct edge{int t,f;edge*nxt,*pair;}*g[N],*d[N],pool[M],*cur=pool;
 struct ISAP{
     int n,m,i,S,T,h[N],gap[N],maxflow;
     void init(int ss,int tt){for(S=ss,T=tt,cur=pool,i=;i<=T;i++)g[i]=d[i]=NULL,h[i]=gap[i]=;}
     void add(int s,int t,int f){
         edge*p=cur++;p->t=t,p->f=f,p->nxt=g[s],g[s]=p;
         p=cur++,p->t=s,p->f=,p->nxt=g[t],g[t]=p;
         g[s]->pair=g[t],g[t]->pair=g[s];
     }
     int sap(int v,int flow){
         if(v==T)return flow;
         int rec=;
         for(edge*p=d[v];p;p=p->nxt)if(h[v]==h[p->t]+&&p->f){
         int ret=sap(p->t,min(flow-rec,p->f));
         p->f-=ret;p->pair->f+=ret;d[v]=p;
         if((rec+=ret)==flow)return flow;
         }
         if(!(--gap[h[v]]))h[S]=T;
         gap[++h[v]]++;d[v]=g[v];
         return rec;
     }
     int get_ans(){
         for(gap[maxflow=]=T,i=;i<=T;i++)d[i]=g[i];
         while(h[S]<T)maxflow+=sap(S,inf);
         return maxflow;
     }
 }G;

 int main(){
     int t,n,m,x,y,c,ic=;
     scanf("%d",&t);
     while(t--){
         scanf("%d%d",&n,&m);//点，边
         G.init(,n);
         F(i,,m)scanf("%d%d%d",&x,&y,&c),G.add(x,y,c);
         printf("Case %d: %d\n",ic++,G.get_ans());
     }
 }