20 lines
499 B
C++
20 lines
499 B
C++
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// st = stack, vis = visited, br = branch(result)
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constexpr int MAXN=1e5+10;
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int dfn[MAXN],low[MAXN],st[MAXN],vis[MAXN],br[MAXN];
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int n,cnt,stn,scn;
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vector<int>ch[MAXN];
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void tarjan(int v){
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dfn[v]=low[v]=++cnt;
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st[stn++]=v;
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vis[v]=1;
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for(const auto&u:ch[v])
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if(!dfn[u])tarjan(u),low[v]=min(low[v],low[u]);
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else if(vis[u])low[v]=min(low[v],dfn[u]);
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if(dfn[v]==low[v]){
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++scn;
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int u;
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do u=st[--stn],vis[u]=0,br[u]=scn; while(u!=v);
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}
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}
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