diff options
Diffstat (limited to 'graph/articulationPoints.cpp')
| -rw-r--r-- | graph/articulationPoints.cpp | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/graph/articulationPoints.cpp b/graph/articulationPoints.cpp index 4bd2243..fba08bb 100644 --- a/graph/articulationPoints.cpp +++ b/graph/articulationPoints.cpp @@ -1,18 +1,18 @@ // Laufzeit: O(|V|+|E|) -vector< vector<int> > adjlist; +vector<vector<int>> adjlist; vector<bool> isArt; vector<int> d, low; -int counter, root; // root >= 2 <=> Wurzel Artikulationspunkt +int counter, root, rootCount; // rootCount >= 2 <=> root Artikulationspunkt vector<ii> bridges; // Nur fuer Brücken. -void dfs(int v, int parent) { // Mit parent=-1 aufrufen. - d[v] = low[v] = counter++; - if (parent == 0) root++; +void dfs(int v, int parent = -1) { + d[v] = low[v] = ++counter; + if (parent == root) ++rootCount; for (auto w : adjlist[v]) { if (!d[w]) { dfs(w, v); - if (low[w] >= d[v]) isArt[v] = true; + if (low[w] >= d[v] && v != root) isArt[v] = true; if (low[w] > d[v]) bridges.push_back(ii(v, w)); low[v] = min(low[v], low[w]); } else if (w != parent) { @@ -20,10 +20,14 @@ void dfs(int v, int parent) { // Mit parent=-1 aufrufen. }}} void findArticulationPoints() { - counter = 1; // Nicht auf 0 setzen! + counter = 0; low.resize(adjlist.size()); d.assign(adjlist.size(), 0); isArt.assign(adjlist.size(), false); bridges.clear(); //nur fuer Bruecken - for (int v = 0; v < (int)adjlist.size(); v++) if (!d[v]) dfs(v, -1); -} + for (int v = 0; v < (int)adjlist.size(); v++) { + if (!d[v]) { + root = v; rootCount = 0; + dfs(v); + if (rootCount > 1) isArt[v] = true; +}}} |