// https://ei1333.github.io/library/template/template.cpp #line 1 "template/template.cpp" #include using namespace std; using int64 = long long; const int mod = 1e9 + 7; const int64 infll = (1LL << 62) - 1; const int inf = (1 << 30) - 1; struct IoSetup { IoSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(10); cerr << fixed << setprecision(10); } } iosetup; template ostream &operator<<(ostream &os, const pair &p) { os << p.first << " " << p.second; return os; } template istream &operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } template ostream &operator<<(ostream &os, const vector &v) { for (int i = 0; i < (int)v.size(); i++) { os << v[i] << (i + 1 != v.size() ? " " : ""); } return os; } template istream &operator>>(istream &is, vector &v) { for (T &in : v) is >> in; return is; } template inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); } template inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); } template vector make_v(size_t a) { return vector(a); } template auto make_v(size_t a, Ts... ts) { return vector(ts...))>(a, make_v(ts...)); } template typename enable_if::value == 0>::type fill_v(T &t, const V &v) { t = v; } template typename enable_if::value != 0>::type fill_v(T &t, const V &v) { for (auto &e : t) fill_v(e, v); } template struct FixPoint : F { explicit FixPoint(F &&f) : F(forward(f)) {} template decltype(auto) operator()(Args &&...args) const { return F::operator()(*this, forward(args)...); } }; template inline decltype(auto) MFP(F &&f) { return FixPoint{forward(f)}; } // https://ei1333.github.io/library/structure/union-find/union-find.cpp #line 1 "structure/union-find/union-find.cpp" /** * @brief Union-Find * @docs docs/union-find.md */ struct UnionFind { vector data; UnionFind() = default; explicit UnionFind(size_t sz) : data(sz, -1) {} bool unite(int x, int y) { x = find(x), y = find(y); if (x == y) return false; if (data[x] > data[y]) swap(x, y); data[x] += data[y]; data[y] = x; return true; } int find(int k) { if (data[k] < 0) return (k); return data[k] = find(data[k]); } int size(int k) { return -data[find(k)]; } bool same(int x, int y) { return find(x) == find(y); } vector> groups() { int n = (int)data.size(); vector> ret(n); for (int i = 0; i < n; i++) { ret[find(i)].emplace_back(i); } ret.erase(remove_if(begin(ret), end(ret), [&](const vector &v) { return v.empty(); }), end(ret)); return ret; } }; // https://ei1333.github.io/library/graph/connected-components/two-edge-connected-components.hpp #line 2 "graph/connected-components/two-edge-connected-components.hpp" #line 2 "graph/graph-template.hpp" /** * @brief Graph Template(グラフテンプレート) */ template struct Edge { int from, to; T cost; int idx; Edge() = default; Edge(int from, int to, T cost = 1, int idx = -1) : from(from), to(to), cost(cost), idx(idx) {} operator int() const { return to; } }; template struct Graph { vector>> g; int es; Graph() = default; explicit Graph(int n) : g(n), es(0) {} size_t size() const { return g.size(); } void add_directed_edge(int from, int to, T cost = 1) { g[from].emplace_back(from, to, cost, es++); } void add_edge(int from, int to, T cost = 1) { g[from].emplace_back(from, to, cost, es); g[to].emplace_back(to, from, cost, es++); } void read(int M, int padding = -1, bool weighted = false, bool directed = false) { for (int i = 0; i < M; i++) { int a, b; cin >> a >> b; a += padding; b += padding; T c = T(1); if (weighted) cin >> c; if (directed) add_directed_edge(a, b, c); else add_edge(a, b, c); } } inline vector> &operator[](const int &k) { return g[k]; } inline const vector> &operator[](const int &k) const { return g[k]; } }; template using Edges = vector>; #line 2 "graph/others/low-link.hpp" #line 4 "graph/others/low-link.hpp" /** * @brief Low Link(橋/関節点) * @see http://kagamiz.hatenablog.com/entry/2013/10/05/005213 * @docs docs/low-link.md */ template struct LowLink : Graph { public: using Graph::Graph; vector ord, low, articulation; vector> bridge; using Graph::g; virtual void build() { used.assign(g.size(), 0); ord.assign(g.size(), 0); low.assign(g.size(), 0); int k = 0; for (int i = 0; i < (int)g.size(); i++) { if (!used[i]) k = dfs(i, k, -1); } } explicit LowLink(const Graph &g) : Graph(g) {} private: vector used; int dfs(int idx, int k, int par) { used[idx] = true; ord[idx] = k++; low[idx] = ord[idx]; bool is_articulation = false, beet = false; int cnt = 0; for (auto &to : g[idx]) { if (to == par && !exchange(beet, true)) { continue; } if (!used[to]) { ++cnt; k = dfs(to, k, idx); low[idx] = min(low[idx], low[to]); is_articulation |= par >= 0 && low[to] >= ord[idx]; if (ord[idx] < low[to]) bridge.emplace_back(to); } else { low[idx] = min(low[idx], ord[to]); } } is_articulation |= par == -1 && cnt > 1; if (is_articulation) articulation.push_back(idx); return k; } }; #line 5 "graph/connected-components/two-edge-connected-components.hpp" /** * @brief Two Edge Connected Components(二重辺連結成分分解) * @docs docs/two-edge-connected-components.md */ template struct TwoEdgeConnectedComponents : LowLink { public: using LowLink::LowLink; using LowLink::g; using LowLink::ord; using LowLink::low; using LowLink::bridge; vector comp; Graph tree; vector> group; int operator[](const int &k) const { return comp[k]; } void build() override { LowLink::build(); comp.assign(g.size(), -1); int k = 0; for (int i = 0; i < (int)comp.size(); i++) { if (comp[i] == -1) dfs(i, -1, k); } group.resize(k); for (int i = 0; i < (int)g.size(); i++) { group[comp[i]].emplace_back(i); } tree = Graph(k); for (auto &e : bridge) { tree.add_edge(comp[e.from], comp[e.to], e.cost); } } explicit TwoEdgeConnectedComponents(const Graph &g) : Graph(g) {} private: void dfs(int idx, int par, int &k) { if (par >= 0 && ord[par] >= low[idx]) comp[idx] = comp[par]; else comp[idx] = k++; for (auto &to : g[idx]) { if (comp[to] == -1) dfs(to, idx, k); } } }; int main() { int n, m, q; cin >> n >> m >> q; TwoEdgeConnectedComponents<> g(n); UnionFind uf(n); for (size_t i = 0; i < m; i++) { int u, v; cin >> u >> v; u--, v--; g.add_edge(u, v); uf.unite(u, v); } g.build(); for (size_t i = 0; i < q; i++) { int x, y; cin >> x >> y; x--, y--; cout << (uf.same(x, y) && g.comp[x] != g.comp[y] ? "Yes" : "No") << '\n'; } return 0; }