UVAlive5135 Mining Your Own Business (BCC)

Title Link: http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=19845

Ideas

Point-double connected component.

To find the BCC, the optimal solution for each BCC is to place an escape device in each BCC with only one cut point.

Code

1#include <cstdio>2#include <cstring>3#include <stack>4#include <vector>5#include <iostream>6#include <cstdlib>7 #definefor (A,B,C) for (int a= (b);a< (c); a++)8 using namespacestd;9 TentypedefLong LongLL; One Const intMAXN =100000+Ten; A  - structedge{intu,v; - }; the  - intpre[maxn],iscut[maxn],bccno[maxn],dfs_clock,bcc_cnt; -vector<int>G[MAXN],BCC[MAXN]; -  +Stack<edge>S; -  + intDfsintUintFA) { A     intlowu=pre[u]=++Dfs_clock; at     intCh=0; -      for(intI=0; I<g[u].size (); i++) { -         intv=G[u][i]; -Edge e=(Edge) {u,v}; -         if(!Pre[v]) { - S.push (e); inch++; -             intlowv=DFS (v,u); tolowu=min (LOWU,LOWV); +             if(lowv>=Pre[u]) { -iscut[u]=1; thebcc_cnt++; Bcc[bcc_cnt].clear (); *                  for(;;) { $Edge x=S.top (); S.pop ();Panax Notoginseng                     if(bccno[x.u]!=bcc_cnt) Bcc[bcc_cnt].push_back (x.u), bccno[x.u]=bcc_cnt; -                     if(bccno[x.v]!=bcc_cnt) Bcc[bcc_cnt].push_back (X.V), bccno[x.v]=bcc_cnt; the                     if(X.u==u && x.v==v) Break; +                 } A             } the         } +         Else if(Pre[v]<pre[u] && v!=FA) { -S.push (e); lowu=min (lowu,pre[v]); $         } $     } -     if(fa<0&& ch==1) iscut[u]=0; -     returnLowu; the } - voidFIND_BCC (intN) {Wuyimemset (PRE,0,sizeof(pre)); thememset (Iscut,0,sizeof(Iscut)); -memset (Bccno,0,sizeof(BCCNO)); WuDfs_clock=bcc_cnt=0; -      for(intI=0; i<n;i++) About         if(!pre[i]) DFS (i,-1); $ } -  - intn,m,kase; -  A intMain () { +      while(SCANF ("%d", &m) &&m) { the         intu,v; -n=0; $          for(intI=0;i<2*m;i++) g[i].clear (); the          for(intI=0; i<m;i++) { thescanf"%d%d",&u,&v); theU--, v--; then=Max (N,max (u,v)); - G[u].push_back (v); in g[v].push_back (u); the         } the          while(!S.empty ()) S.pop (); About          the FIND_BCC (n); the          theLL ans1=0, ans2=1; +          for(intI=1; i<=bcc_cnt;i++) { -             intCnt=0; the              for(intj=0; J<bcc[i].size (); j + +)Bayi                 if(Iscut[bcc[i][j]]) cnt++; the             if(cnt==1) { theans1++; Ans2*= (Long Long) (Bcc[i].size ()-1); -             } -         } the         if(bcc_cnt==1) { theans1=2; ans2=bcc[1].size () * (bcc[1].size ()-1)/2; the         } theprintf"Case %d:%lld%lld\n",++kase,ans1,ans2); -     } the     return 0; the}

UVAlive5135 Mining Your Own Business (BCC)