#include <bits/stdc++.h> #define ll long long #define all(x) x.begin(), x.end() #define Neco "Neco" #define resp(x) sort(all(x)), x.resize(unique(all(x)) - x.begin()) #define getbit(x,i) ((x >> i)&1) #define _left id * 2, l, mid #define _right id * 2 + 1, mid + 1, r #define cntbit(x) __builtin_popcountll(x) #define fi(i, a, b) for(int i = a; i <= b; i++) #define fid(i, a, b) for(int i = a; i >= b; i--) #define maxn (int) (120000 + 3) using namespace std; const ll mod = 1e9 + 7; //972663749 const ll base = 911382323; mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); ll GetRandom(ll l, ll r) { return uniform_int_distribution<ll> (l, r)(rng); } const int LOG = 17; void Input(); void reset(); int n, m; vector<int> edges[maxn], g[36 * maxn]; int cha[maxn][18], idUP[maxn][18], idDOWN[maxn][18]; int S[maxn], T[maxn], h[maxn]; int ID_S[maxn], ID_T[maxn]; void pre_dfs(int u, int par) { for(int v : edges[u]) if(v != par) { cha[v][0] = u, h[v] = h[u] + 1; fi(i, 1, LOG) cha[v][i] = cha[cha[v][i - 1]][i - 1]; pre_dfs(v, u); } } int lca(int u, int v) { if(h[u] < h[v]) swap(u, v); fid(i, LOG, 0) if(h[u] - (1 << i) >= h[v]) u = cha[u][i]; if(u == v) return u; fid(i, LOG, 0) if(cha[u][i] != cha[v][i]) { u = cha[u][i], v = cha[v][i]; } return cha[u][0]; } int ID_mapping() { int IDN = m; fi(i, 1, n) ID_S[i] = ++IDN, ID_T[i] = ++IDN; fi(i, 1, m) ID_S[S[i]] = ID_T[T[i]] = i; fi(i, 1, n) fi(j, 1, LOG) if(cha[i][j]) { idUP[i][j] = ++IDN; idDOWN[i][j] = ++IDN; } fi(i, 1, n) if(cha[i][0]) { idUP[i][0] = ID_S[cha[i][0]]; idDOWN[i][0] = ID_T[cha[i][0]]; } auto connect = [](int u, int v) { if(u == 0 || v == 0) return; g[u].push_back(v); }; fi(j, 1, LOG) { fi(i, 1, n) if(cha[i][j]) { connect(idUP[i][j - 1], idUP[i][j]); connect(idUP[cha[i][j - 1]][j - 1], idUP[i][j]); connect(idDOWN[i][j], idDOWN[i][j - 1]); connect(idDOWN[i][j], idDOWN[cha[i][j - 1]][j - 1]); } } return IDN; } void AddS(int u, int p, int id) { fid(i, LOG, 0) if(h[u] - (1 << i) > h[p]) { g[idUP[u][i]].push_back(id); // cout << u << " " << idUP[u][i] << " " << id << '\n'; u = cha[u][i]; } } void AddT(int u, int p, int id) { fid(i, LOG, 0) if(h[u] - (1 << i) > h[p]) { g[id].push_back(idDOWN[u][i]); u = cha[u][i]; } } bool topoSort(int N) { vector<int> deg(N + 1, 0); fi(i, 1, N) for(int v : g[i]) deg[v] ++; queue<int> q; fi(i, 1, N) if(!deg[i]) q.push(i); while(!q.empty()) { int u = q.front(); q.pop(); for(int v : g[u]) if(--deg[v] == 0) { q.push(v); } } fi(i, 1, N) g[i].clear(); return *max_element(all(deg)) == 0; } void solve() { Input(); if(m > 500) return; pre_dfs(1, 0); int N = ID_mapping(); fi(i, 1, m) { int u = S[i], v = T[i], p = lca(S[i], T[i]); AddS(u, p, i); AddS(v, p, i); AddT(u, p, i); AddT(v, p, i); g[ID_S[v]].push_back(i); g[i].push_back(ID_T[u]); if(u != p) g[ID_S[p]].push_back(i); if(v != p) g[i].push_back(ID_T[p]); } if(topoSort(N)) cout << "Yes\n"; else cout << "No\n"; reset(); } void Input() { cin >> n; fi(i, 1, n - 1) { int x, y; cin >> x >> y; edges[x].push_back(y); edges[y].push_back(x); } cin >> m; fi(i, 1, m) cin >> S[i] >> T[i]; } void reset() { fi(i, 1, n) edges[i].clear(); fi(i, 1, n) fi(j, 0, LOG) cha[i][j] = idUP[i][j] = idDOWN[i][j] = 0; } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); if(fopen(Neco".inp", "r")) { freopen(Neco".inp", "r", stdin); freopen(Neco".out", "w", stdout); } int nTest = 1; cin >> nTest; while(nTest--) { solve(); } return 0; }

jail.cpp: In function 'int main()':
jail.cpp:182:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  182 |         freopen(Neco".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
jail.cpp:183:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  183 |         freopen(Neco".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~