15 lines
528 B
C++
15 lines
528 B
C++
int d[MX], L[MX][20];
|
|
void dfs(int u = 1, int p = 0) {
|
|
d[u] = d[p] + 1, L[u][0] = p;
|
|
for (int i = 0; i < 18 && L[u][i]; i++) L[u][i+1] = L[L[u][i]][i];
|
|
for (auto & v : G[u]) if (v != p) dfs(v, u);
|
|
}
|
|
int lca(int u, int v) {
|
|
if (d[u] > d[v]) swap(u, v);
|
|
for (int i = 18; i >= 0; --i) if (d[v] - (1<<i) >= d[u]) v = L[v][i];
|
|
if (u == v) return u;
|
|
for (int i = 18; i >= 0; --i) if (L[u][i] && L[u][i] != L[v][i]) u = L[u][i], v = L[v][i];
|
|
return L[u][0];
|
|
}
|
|
inline int dist(int u, int v) { return d[u]+d[v]-2*d[lca(u, v)]; }
|