vector <int> Q[N];int Find(int x){if(x != fa[x]) return fa[x] = Find(fa[x]);return x;}void Union(int x, int y){int fx = Find(x), fy = Find(y);if(fy != fx) fa[fy] = fx;}void dfs(int u){anc[u] = u;for(int i = head[u]; ~i; i = e[i].next) {int v = e[i].v;dfs(v);Union(u, v);anc[Find(u)] = u;}vis[u] = true;int sz = Q[u].size();for(int i = 0; i < sz; i++) {int v = Q[u][i];if(vis[v]) {printf(“%d\n”, anc[Find(v)]);return ;}}}
，再怎么风光明媚的自家山川，
