#include #include namespace nachia{ struct AdjacencyList{ public: struct AdjacencyListRange{ using iterator = typename std::vector::const_iterator; iterator begi, endi; iterator begin() const { return begi; } iterator end() const { return endi; } int size() const { return (int)std::distance(begi, endi); } const int& operator[](int i) const { return begi[i]; } }; private: int mn; std::vector E; std::vector I; public: AdjacencyList(int n, std::vector> edges, bool rev){ mn = n; std::vector buf(n+1, 0); for(auto [u,v] : edges){ ++buf[u]; if(rev) ++buf[v]; } for(int i=1; i<=n; i++) buf[i] += buf[i-1]; E.resize(buf[n]); for(int i=(int)edges.size()-1; i>=0; i--){ auto [u,v] = edges[i]; E[--buf[u]] = v; if(rev) E[--buf[v]] = u; } I = std::move(buf); } AdjacencyList(const std::vector>& edges = {}){ int n = mn = edges.size(); std::vector buf(n+1, 0); for(int i=0; i targets, std::vector bounds){ AdjacencyList res; res.mn = bounds.size() - 1; res.E = std::move(targets); res.I = std::move(bounds); return res; } AdjacencyListRange operator[](int u) const { return AdjacencyListRange{ E.begin() + I[u], E.begin() + I[u+1] }; } int num_vertices() const { return mn; } int num_edges() const { return E.size(); } AdjacencyList reversed_edges() const { AdjacencyList res; int n = res.mn = mn; std::vector buf(n+1, 0); for(int v : E) ++buf[v]; for(int i=1; i<=n; i++) buf[i] += buf[i-1]; res.E.resize(buf[n]); for(int u=0; u::const_iterator; iterator begi, endi; iterator begin() const { return begi; } iterator end() const { return endi; } int size() const { return (int)std::distance(begi, endi); } const Edge& operator[](int i) const { return begi[i]; } }; private: int mn; std::vector E; std::vector I; public: AdjacencyListEdgeIndexed(int n, const std::vector>& edges, bool rev){ mn = n; std::vector buf(n+1, 0); for(auto [u,v] : edges){ ++buf[u]; if(rev) ++buf[v]; } for(int i=1; i<=n; i++) buf[i] += buf[i-1]; E.resize(buf[n]); for(int i=(int)edges.size()-1; i>=0; i--){ auto [u,v] = edges[i]; E[--buf[u]] = { v, i }; if(rev) E[--buf[v]] = { u, i }; } I = std::move(buf); } AdjacencyListEdgeIndexed() : AdjacencyListEdgeIndexed(0, {}, false) {} AdjacencyListRange operator[](int u) const { return AdjacencyListRange{ E.begin() + I[u], E.begin() + I[u+1] }; } int num_vertices() const { return mn; } int num_edges() const { return E.size(); } AdjacencyListEdgeIndexed reversed_edges() const { AdjacencyListEdgeIndexed res; int n = res.mn = mn; std::vector buf(n+1, 0); for(auto [v,i] : E) ++buf[v]; for(int i=1; i<=n; i++) buf[i] += buf[i-1]; res.E.resize(buf[n]); for(int u=0; u #include namespace nachia{ class BiconnectedComponents{ private: int mn; int mm; int mnum_bcs; std::vector> medges; std::vector edgeidx_to_bcidx; public: BiconnectedComponents(int n, std::vector> edges){ std::vector dfsi_to_vtx; std::vector vtx_to_dfsi; std::vector linked_over; std::vector dfs_parent; mn = n; int m = edges.size(); medges = std::move(edges); nachia::AdjacencyListEdgeIndexed adj(n, medges, true); dfsi_to_vtx.resize(n); vtx_to_dfsi.resize(n); dfs_parent.assign(n, -1); linked_over.assign(n, -1); int dfsi = 0; auto dfs1 = [&](int p, auto self)->int { vtx_to_dfsi[p] = dfsi; dfsi_to_vtx[dfsi] = p; int backedge = dfsi; dfsi++; for(auto [nx,i] : adj[p]){ if(dfs_parent[nx] != -1) backedge = std::min(backedge, vtx_to_dfsi[nx]); else{ dfs_parent[nx] = i; int link = self(nx, self); backedge = std::min(backedge, link); linked_over[nx] = (link < vtx_to_dfsi[p]) ? 1 : 0; } } return backedge; }; for(int i=0; i res(m); auto dfs2 = [&](int p, int bcid, int& maxbcid, auto self)-> void { if(dfs_parent[p] < 0){ for(auto [nx,i] : adj[p]) if(dfs_parent[nx] == i){ bcid = maxbcid++; self(nx, bcid, maxbcid, self); } return; } for(auto [nx,i] : adj[p]) if(dfs_parent[nx] != i) res[i] = bcid; for(auto [nx,i] : adj[p]) if(dfs_parent[nx] == i){ int nx_bcid = bcid; if(!linked_over[nx]) nx_bcid = maxbcid++; self(nx, nx_bcid, maxbcid, self); } }; int bcid = 0; for(int i=0; i> get_bcs() const { std::vector> res(mnum_bcs); for(int i=0; i buf(mnum_bcs+1); for(int bci : edgeidx_to_bcidx) ++buf[bci]; for(int i=1; i<=mnum_bcs; i++) buf[i] += buf[i-1]; std::vector E(buf.back()); for(int i=0; i> res(bct_n - 1); int resi = 0; std::vector visited(mn); for(int bci=0; bci using namespace std; #define rep(i,n) for(int i=0; i<(n); i++) struct HLD{ int N; vector P; vector PP; vector PD; vector D; HLD(const nachia::AdjacencyList& E = nachia::AdjacencyList(1,{},false)){ N = E.num_vertices(); P.assign(N, -1); vector I = {0}; for(int i=0; i<(int)I.size(); i++){ int p = I[i]; for(int e : E[p]) if(P[p] != e){ I.push_back(e); P[e] = p; } } vector Z(N, 1); for(int i=N-1; i>=1; i--) Z[P[I[i]]] += Z[I[i]]; PP.resize(N); for(int i=0; i nx(N, -1); for(int p : I) if(p != 0){ if(nx[P[p]] == -1) nx[P[p]] = p; if(Z[nx[P[p]]] < Z[p]) nx[P[p]] = p; } for(int i=0; i PD[v]) u = P[PP[u]]; while(PP[u] != PP[v]){ u = P[PP[u]]; v = P[PP[v]]; } return (D[u] > D[v]) ? v : u; } vector> lcaP; void fastLcaInit(){ lcaP.assign(5,vector(N,0)); for(int i=0; i=0; d--) if(PD[u]-PD[v] >= (1<=0; d--) if(lcaP[d][u] != lcaP[d][v]){ u = lcaP[d][u]; v = lcaP[d][v]; } if(PP[u] != PP[v]){ u = lcaP[0][u]; v = lcaP[0][v]; } return (D[u] > D[v]) ? v : u; } int dist(int u, int v){ int g = fastLca(u,v); return D[u] + D[v] - D[g] * 2; } }; #include int main() { int n; cin >> n; int m; cin >> m; std::vector> edges(m); for(auto& [u,v] : edges){ cin >> u >> v; u--; v--; } auto hld_bct = HLD(nachia::BiconnectedComponents(n, edges).get_bct()); hld_bct.fastLcaInit(); int q; cin >> q; for(int queryi=0; queryi> u >> v; u--; v--; int d = hld_bct.dist(u,v); int ans = std::max(0, d/2-1); cout << ans << "\n"; } return 0; } struct ios_do_not_sync{ ios_do_not_sync(){ ios::sync_with_stdio(false); cin.tie(nullptr); } } ios_do_not_sync_instance;