52 lines
1.2 KiB
Lua
52 lines
1.2 KiB
Lua
return [=[
|
|
// WARN: Input should be a simple graph
|
|
//
|
|
// Returns: (BCC count, indices of BCC of each vertex)
|
|
//
|
|
// BCC index starts from 1
|
|
pair<int, vector<int>> ebcc(const vector<vector<int>>& ch) {
|
|
int n = ch.size() - 1;
|
|
vector<int> c(n + 1);
|
|
|
|
vector<int> low(n + 1), dfn(n + 1);
|
|
vector<bool> vis(n + 1);
|
|
vector<int> stack;
|
|
|
|
int time = 0;
|
|
int cnt = 0;
|
|
|
|
auto dfs = [&] (auto dfs, int v, int pa) -> void {
|
|
low[v] = dfn[v] = ++time;
|
|
stack.emplace_back(v);
|
|
vis[v] = 1;
|
|
for (auto&& u : ch[v]) {
|
|
if (u == pa) continue;
|
|
if (not dfn[u]) {
|
|
dfs(dfs, u, v);
|
|
chmin(low[v], low[u]);
|
|
} else if (vis[u]) {
|
|
chmin(low[v], dfn[u]);
|
|
}
|
|
}
|
|
if (dfn[v] == low[v]) {
|
|
cnt += 1;
|
|
c[v] = cnt;
|
|
while (stack.back() != v) {
|
|
c[stack.back()] = cnt;
|
|
vis[stack.back()] = 0;
|
|
stack.pop_back();
|
|
}
|
|
stack.pop_back();
|
|
}
|
|
};
|
|
|
|
for (int i = 1; i <= n; ++i) {
|
|
if (not dfn[i]) {
|
|
dfs(dfs, i, 0);
|
|
}
|
|
}
|
|
return { cnt, c };
|
|
}
|
|
|
|
]=]
|