Envío 5627

Código

#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < n; i++)
#define pb push_back
#define ff first
#define ss second
#define ii pair<int, int>
#define vi vector<int>
#define vii vector<ii>
#define lli long long int
#define fast_io                                                                \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0);
using namespace std;
ostream &operator<<(ostream &os, const vector<int> &v) {
  for (auto const &i : v) {
    os << i << " ";
  }
  os << endl;
  return os;
}
const lli mod = (1e9) + 7;
const int N = 1e4 + 1;
const int oo = 1e9 + 7;
int t;
void dfs(vector<vi> &g, vector<bool> &visited, vii &time, int s) {
  visited[s] = true;
  time[s].ff = t;
  for (auto veci : g[s]) {
    if (!visited[veci]) {
      t++;
      dfs(g, visited, time, veci);
    }
  }
  t++;
  time[s].ss = t;
}
int main() {
  fast_io;
  int n;
  cin >> n;
  vector<vector<int>> g(n); // just save father of node
  vii time(n, ii(oo, oo));
  vector<bool> visited(n, false);
  int p, h;
  vi ind(n, 0);
  REP(i, n - 1) {
    cin >> p >> h;
    g[h].pb(p);
    g[p].pb(h);
    ind[h]++;
  }
  int root;
  REP(i, n) {
    if (!ind[i])
      root = i;
  }
  // cout<<"Root "<<root<<endl;
  dfs(g, visited, time, root);
  int c;
  cin >> c;
  int a, b;
  while (c--) {
    cin >> a >> b; // check if a is ancestor of b
    auto timeA = time[a];
    auto timeB = time[b];
    if (a == b) {
      cout << "Yes" << endl;
      continue;
    }
    if (timeA.ff < timeB.ff && timeA.ss > timeB.ss)
      cout << "Yes" << endl;
    else
      cout << "No" << endl;
  }
  return 0;
}