POJ3084 Panic (min cut)

The minimum cost of separating a point from a certain point, of course, is to think of the smallest cut. Specifically how to build a diagram, you can draw a simple situation, and then clear:

0 to 1 uncontrolled, establishes 0->1 capacity for the edge of the INF;

1 to 0 is controlled by a control panel on the 1 side, establishing an edge of 1->0 capacity of 1.

1#include <cstdio>2#include <cstring>3#include <queue>4#include <algorithm>5 using namespacestd;6 #defineINF (1&LT;&LT;30)7 #defineMAXN 228 #defineMAXM 88889 Ten structedge{ One     intV,cap,flow,next; A }EDGE[MAXM]; - intVs,vt,ne,nv; - intHEAD[MAXN]; the  - voidAddedge (intUintVintcap) { -Edge[ne].v=v; Edge[ne].cap=cap; edge[ne].flow=0; -Edge[ne].next=head[u]; head[u]=ne++; +Edge[ne].v=u; edge[ne].cap=0; edge[ne].flow=0; -EDGE[NE].NEXT=HEAD[V]; head[v]=ne++; + } A  at intLEVEL[MAXN]; - intGAP[MAXN]; - voidBFs () { -memset (level,-1,sizeof(level)); -Memset (Gap,0,sizeof(GAP)); -level[vt]=0; ingap[level[vt]]++; -queue<int>que; to Que.push (VT); +      while(!Que.empty ()) { -         intu=Que.front (); Que.pop (); the          for(intI=head[u]; i!=-1; I=Edge[i].next) { *             intv=edge[i].v; $             if(level[v]!=-1)Continue;Panax Notoginsenglevel[v]=level[u]+1; -gap[level[v]]++; the Que.push (v); +         } A     } the } +  - intPRE[MAXN]; $ intCUR[MAXN]; $ intIsap () { - BFS (); -memset (pre,-1,sizeof(pre)); thememcpy (Cur,head,sizeof(head)); -     intu=pre[vs]=vs,flow=0, aug=INF;Wuyigap[0]=NV; the      while(level[vs]<NV) { -         BOOLflag=false; Wu          for(int&i=cur[u]; i!=-1; I=Edge[i].next) { -             intv=edge[i].v; About             if(Edge[i].cap!=edge[i].flow && level[u]==level[v]+1){ $flag=true; -pre[v]=u; -u=v; -                 //aug= (Aug==-1?edge[i].cap:min (Aug,edge[i].cap)); AAug=min (aug,edge[i].cap-edge[i].flow); +                 if(v==VT) { theflow+=; -                      for(u=pre[v]; V!=vs; v=u,u=Pre[u]) { $edge[cur[u]].flow+=; theedge[cur[u]^1].flow-=; the                     } the                     //Aug=-1; theaug=INF; -                 } in                  Break; the             } the         } About         if(flag)Continue; the         intMinlevel=NV; the          for(intI=head[u]; i!=-1; I=Edge[i].next) { the             intv=edge[i].v; +             if(Edge[i].cap!=edge[i].flow && level[v]<minlevel) { -Minlevel=Level[v]; thecur[u]=i;Bayi             } the         } the         if(--gap[level[u]]==0) Break; -level[u]=minlevel+1; -gap[level[u]]++; theu=Pre[u]; the     } the     returnflow; the } - intMain () { the     intt,n,a,b; the     Chars[ One]; thescanf"%d",&t);94      while(t--){ thescanf"%d%d",&n,&VT); theVs=n; nv=n+1; Ne=0; thememset (head,-1,sizeof(head));98          for(intI=0; i<n; ++i) { Aboutscanf"%s", s); -             if(s[0]=='I') Addedge (vs,i,inf);101scanf"%d",&a);102              while(a--){103scanf"%d",&b);104 Addedge (i,b,inf); theAddedge (B,i,1);106             }107         }108         intres=Isap ();109         if(res>10000000) puts ("PANIC BREACH"); the         Elseprintf"%d\n", res);111     } the     return 0;113}

POJ3084 Panic (min cut)