最大流

#define N 10000 int n,m,len,s,t;struct node{int x,y,e,pre;};node a[N*2];int pre[N],que[N],stage[N];void init(){len=0; s=0; t=m+n+1;//s和t自己改的memset(pre,-1,sizeof(pre));}void addpage(int x,int y,int t){a[len].x=x;a[len].y=y;a[len].e=t;a[len].pre=pre[x];pre[x]=len++;}bool bfs(){queue<int>q;memset(stage,-1,sizeof(stage));stage[s]=0; q.push(s);while(!q.empty()){int x=q.front(); q.pop();for(int i=pre[x]; i!=-1; i=a[i].pre)if(a[i].e>0 && stage[a[i].y]==-1){stage[a[i].y]=stage[a[i].x]+1;q.push(a[i].y);if(a[i].y==t) return true;}}return false;}int dfs(){int sum=0;while(bfs()){int tail=0,u=s;while(true){if(u==t)            {int Min=inf,mark;rep(i,tail)if(a[que[i]].e<Min)mark=i,Min=a[que[i]].e;rep(i,tail)a[que[i]].e-=Min,a[que[i]^1].e+=Min;sum+=Min,tail=mark,u=a[que[tail]].x;            }int i;for( i=pre[u]; i!=-1; i=a[i].pre){int y=a[i].y;if(stage[y]==-1) continue;                if(stage[y]==stage[u]+1 && a[i].e>0) break;}if(i!=-1)//回朔que[tail++]=i,u=a[i].y;else{if(tail==0) break;stage[u]=-1;u=a[que[--tail]].x;}}}return sum;}int main(){ init();//加正反边return dfs();   return 0;}