Point-Dual-connectivity component template

By: White Book

#define M 10000int pre[M],dfs_clock,iscut[M],low[M],bcc_cnt,bccno[M];vector<int>G[M],bcc[M];struct Edge{int u,v;Edge(int from,int to){u=from;v=to;}};stack<Edge> S;int dfs(int u,int fa){int lowu=pre[u]=++dfs_clock;int child=0;for(int i=0;i<G[u].size();i++){int v=G[u][i];Edge e = Edge(u,v);if(!pre[v]){S.push(e);child++;int lowv=dfs(v,u);lowu=min(lowv,lowu);if(lowv>=pre[u]){iscut[u]=true;bcc_cnt++;bcc[bcc_cnt].clear();for(;;){Edge x = S.top();S.pop();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;}if(x.u==u&&x.v==v) break;}}}else if(pre[v]<pre[u]&&v!=fa){S.push(e);lowu=min(lowu,pre[v]);}}if(fa<0&&child==1) iscut[u]=0;return lowu;}void find_bcc(int n){memset(pre,0,sizeof(pre));memset(iscut,0,sizeof(iscut));memset(bccno,0,sizeof(bccno));dfs_clock=bcc_cnt=0;for(int i=0;i<n;i++)if(!pre[i]) dfs(i,-1);}