LCA(倍增)

inline void dfs(int u, int f)
{
fa[u][0] = f;
dep[u] = dep[f] + 1;
for(int i = 1; i <= 26; ++i)
fa[u][i] = fa[fa[u][i - 1]][i - 1];
int v;
for(int e = hd[u]; e; e = nt[e])
if((v = to[e]) ^ f)
dfs(v, u);
}
inline int LCA(int u, int v)
{
if(dep[u] < dep[v]) swap(u, v);
if(u == v) return u;
for(int i = 26; i >= 0; --i)
if(dep[fa[u][i]] >= dep[v])
u = fa[u][i];
if(u == v) return u;
for(int i = 26; i >= 0; --i)
if(fa[u][i] ^ fa[v][i])
u = fa[u][i], v = fa[v][i];
return fa[u][0];
}

标签：dep,26,return,int,dfs,fa,LCA,倍增
来源： https://www.cnblogs.com/fakeryu/p/16410717.html