【求割边】

Max_Flow<int> MF;int n,m;int main(){    while(scanf("%d%d",&n,&m) != EOF){if(n == 0 && m == 0) break;MF.Init(n+5,1,n);int u,v,w;for(int i=0;i<m;i++){scanf("%d%d%d",&u,&v,&w);MF.Add_edge(u,v,w);}MF.ChangeST(1,2);int ret = MF.Dinic();for(int i=1;i<=n;i++){if(level[i] == -1) continue;for(int ei=head[i];ei!=-1;ei=nxt[ei]){if(level[pnt[ei]] == -1){printf("%d %d\n",i,pnt[ei]);}}}puts("");}    return 0;}