1 const int N = 1e5 + 5; 2 vector<int> g[N]; 3 int fa[N], dp[N], sz[N], son[N], top[N], dfn[N], to[N], cnt = 0, n; 4 void dfs1(int u, int o) { 5 fa[u] = o; 6 sz[u] = 1; 7 dp[u] = dp[o] + 1; 8 for (int i = 0; i < g[u].size(); ++i) { 9 int v = g[u][i]; 10 if(v != o) { 11 dfs1(v, u); 12 sz[u] += sz[v]; 13 if(sz[v] > sz[son[u]]) son[u] = v; 14 } 15 } 16 } 17 void dfs2(int u, int t) { 18 top[u] = t; 19 dfn[u] = ++cnt; 20 to[cnt] = u; 21 if(!son[u]) return ; 22 dfs2(son[u], t); 23 for (int i = 0; i < g[u].size(); ++i) { 24 int v = g[u][i]; 25 if(v != fa[u] && v != son[u]) dfs2(v, v); 26 } 27 } 28 void add(int u, int v, int x) { 29 int fu = top[u], fv = top[v]; 30 while(fu != fv) { 31 if(dp[fu] >= dp[fv]) update(dfn[fu], dfn[u], x, 1, 1, n), u = fa[fu], fu = top[u]; 32 else update(dfn[fv], dfn[v], x, 1, 1, n), v = fa[fv], fv = top[v]; 33 } 34 if(dfn[u] <= dfn[v]) update(dfn[u], dfn[v], x, 1, 1, n); 35 else update(dfn[v], dfn[u], x, 1, 1, n); 36 } 37 int sum(int u, int v) { 38 int ans = 0, fu = top[u], fv = top[v]; 39 while(fu != fv) { 40 if(dp[fu] >= dp[fv]) ans += query(dfn[fu], dfn[u], 1, 1, n), u = fa[fu], fu = top[u]; 41 else ans += query(dfn[fv], dfn[v], 1, 1, n), v = fa[fv], fv = top[v]; 42 } 43 if(dfn[u] <= dfn[v]) ans += query(dfn[u], dfn[v], 1, 1, n); 44 else ans += query(dfn[v], dfn[u], 1, 1, n); 45 return ans; 46 } 47 int lca(int u, int v) { 48 int fu = top[u], fv = top[v]; 49 while(fu != fv) { 50 if(dp[fu] >= dp[fv]) u = fa[fu], fu = top[u]; 51 else v = fa[fv], fv = top[v]; 52 } 53 if(dp[u] <= dp[v]) return u; 54 else v; 55 }