#line 2 "nachia\\array\\csr-array.hpp" #include #include #include namespace nachia{ template class CsrArray{ public: struct ListRange{ using iterator = typename std::vector::iterator; iterator begi, endi; iterator begin() const { return begi; } iterator end() const { return endi; } int size() const { return (int)std::distance(begi, endi); } Elem& operator[](int i) const { return begi[i]; } }; struct ConstListRange{ 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 Elem& operator[](int i) const { return begi[i]; } }; private: int m_n; std::vector m_list; std::vector m_pos; public: CsrArray() : m_n(0), m_list(), m_pos() {} static CsrArray Construct(int n, const std::vector>& items){ CsrArray res; res.m_n = n; std::vector buf(n+1, 0); for(auto& [u,v] : items){ ++buf[u]; } for(int i=1; i<=n; i++) buf[i] += buf[i-1]; res.m_list.resize(buf[n]); for(int i=(int)items.size()-1; i>=0; i--){ res.m_list[--buf[items[i].first]] = items[i].second; } res.m_pos = std::move(buf); return res; } static CsrArray FromRaw(std::vector list, std::vector pos){ CsrArray res; res.m_n = pos.size() - 1; res.m_list = std::move(list); res.m_pos = std::move(pos); return res; } ListRange operator[](int u) { return ListRange{ m_list.begin() + m_pos[u], m_list.begin() + m_pos[u+1] }; } ConstListRange operator[](int u) const { return ConstListRange{ m_list.begin() + m_pos[u], m_list.begin() + m_pos[u+1] }; } int size() const { return m_n; } int fullSize() const { return (int)m_list.size(); } }; } // namespace nachia #line 5 "nachia\\tree\\heavy-light-decomposition.hpp" namespace nachia{ struct HeavyLightDecomposition{ private: int N; std::vector P; std::vector PP; std::vector PD; std::vector D; std::vector I; std::vector rangeL; std::vector rangeR; public: HeavyLightDecomposition(const CsrArray& E = CsrArray::Construct(1, {})){ N = E.size(); P.assign(N, -1); I = {0}; I.reserve(N); 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; } } std::vector Z(N, 1); std::vector nx(N, -1); PP.resize(N); for(int i=0; i=1; i--){ int p = I[i]; Z[P[p]] += Z[p]; if(nx[P[p]] == -1) nx[P[p]] = p; if(Z[nx[P[p]]] < Z[p]) nx[P[p]] = p; } for(int p : I) if(nx[p] != -1) PP[nx[p]] = p; PD.assign(N,N); PD[0] = 0; D.assign(N,0); for(int p : I) if(p != 0){ PP[p] = PP[PP[p]]; PD[p] = std::min(PD[PP[p]], PD[P[p]]+1); D[p] = D[P[p]]+1; } rangeL.assign(N,0); rangeR.assign(N,0); for(int p : I){ rangeR[p] = rangeL[p] + Z[p]; int ir = rangeR[p]; for(int e : E[p]) if(P[p] != e) if(e != nx[p]){ rangeL[e] = (ir -= Z[e]); } if(nx[p] != -1){ rangeL[nx[p]] = rangeL[p] + 1; } } I.resize(N); 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; } int dist(int u, int v) const { return depth(u) + depth(v) - depth(lca(u,v)) * 2; } std::vector> path(int r, int c, bool include_root = true, bool reverse_path = false) const { if(PD[c] < PD[r]) return {}; std::vector> res(PD[c]-PD[r]+1); for(int i=0; i<(int)res.size()-1; i++){ res[i] = std::make_pair(rangeL[PP[c]], rangeL[c]+1); c = P[PP[c]]; } if(PP[r] != PP[c] || D[r] > D[c]) return {}; res.back() = std::make_pair(rangeL[r]+(include_root?0:1), rangeL[c]+1); if(res.back().first == res.back().second) res.pop_back(); if(!reverse_path) std::reverse(res.begin(),res.end()); else for(auto& a : res) a = std::make_pair(N - a.second, N - a.first); return res; } std::pair subtree(int p){ return std::make_pair(rangeL[p], rangeR[p]); } int median(int x, int y, int z) const { return lca(x,y) ^ lca(y,z) ^ lca(x,z); } int la(int from, int to, int d) const { if(d < 0) return -1; int g = lca(from,to); int dist0 = D[from] - D[g] * 2 + D[to]; if(dist0 < d) return -1; int p = from; if(D[from] - D[g] < d){ p = to; d = dist0 - d; } while(D[p] - D[PP[p]] < d){ d -= D[p] - D[PP[p]] + 1; p = P[PP[p]]; } return I[rangeL[p] - d]; } }; } // namespace nachia #line 4 "nachia\\graph\\graph.hpp" #include #line 6 "nachia\\graph\\graph.hpp" namespace nachia{ struct Graph { public: struct Edge{ int from, to; void reverse(){ std::swap(from, to); } }; using Base = std::vector>; Graph(int n = 0, bool undirected = false) : m_n(n), m_e(), m_isUndir(undirected) {} Graph(int n, const std::vector>& edges, bool undirected = false) : m_n(n), m_isUndir(undirected){ m_e.resize(edges.size()); for(std::size_t i=0; i& edges, bool undirected = false) : m_n(n), m_e(edges), m_isUndir(undirected) {} Graph(int n, std::vector&& edges, bool undirected = false) : m_n(n), m_e(edges), m_isUndir(undirected) {} int numVertices() const noexcept { return m_n; } int numEdges() const noexcept { return int(m_e.size()); } int addEdge(int from, int to){ m_e.push_back({ from, to }); return numEdges() - 1; } Edge& operator[](int ei) noexcept { return m_e[ei]; } const Edge& operator[](int ei) const noexcept { return m_e[ei]; } Edge& at(int ei) { return m_e.at(ei); } const Edge& at(int ei) const { return m_e.at(ei); } auto begin(){ return m_e.begin(); } auto end(){ return m_e.end(); } auto begin() const { return m_e.begin(); } auto end() const { return m_e.end(); } bool isUndirected() const noexcept { return m_isUndir; } void reverseEdges() noexcept { for(auto& e : m_e) e.reverse(); } void contract(int newV, const std::vector& mapping){ assert(numVertices() == int(mapping.size())); for(int i=0; i induce(int num, const std::vector& mapping) const { int n = numVertices(); assert(n == int(mapping.size())); for(int i=0; i indexV(n), newV(num); for(int i=0; i= 0) indexV[i] = ++newV[mapping[i]]; std::vector res; res.reserve(num); for(int i=0; i= 0) res[mapping[e.to]].addEdge(indexV[e.from], indexV[e.to]); return res; } CsrArray getEdgeIndexArray(bool undirected) const { std::vector> src; src.reserve(numEdges() * (undirected ? 2 : 1)); for(int i=0; i::Construct(numVertices(), src); } CsrArray getEdgeIndexArray() const { return getEdgeIndexArray(isUndirected()); } CsrArray getAdjacencyArray(bool undirected) const { std::vector> src; src.reserve(numEdges() * (undirected ? 2 : 1)); for(auto e : m_e){ src.emplace_back(e.from, e.to); if(undirected) src.emplace_back(e.to, e.from); } return CsrArray::Construct(numVertices(), src); } CsrArray getAdjacencyArray() const { return getAdjacencyArray(isUndirected()); } private: int m_n; std::vector m_e; bool m_isUndir; }; } // namespace nachia #line 3 "nachia\\graph\\dfs-tree.hpp" namespace nachia{ struct DfsTree{ std::vector dfsOrd; std::vector parent; template static DfsTree Construct(const CsrArray& adj){ DfsTree res; int n = adj.size(); res.dfsOrd.resize(n); int Oi = 0; std::vector eid(n, 0), parent(n, -2); for(int s=0; s= n) p -= n; parent[p] = -1; while(0 <= p){ if(eid[p] == (OutOrd ? (int)adj[p].size() : 0)) res.dfsOrd[Oi++] = p; if(eid[p] == (int)adj[p].size()){ p = parent[p]; continue; } int nx = adj[p][eid[p]++]; if(parent[nx] != -2) continue; parent[nx] = p; p = nx; } } res.parent = std::move(parent); return res; } template static DfsTree Construct(const Graph& g){ return Construct(g.getAdjacencyArray()); } }; } // namespace nachia #line 6 "nachia\\graph\\biconnected-components.hpp" namespace nachia{ class BiconnectedComponents{ private: int mn; int mm; int mnum_bcs; Graph mG; std::vector> m_bcVtxPair; public: BiconnectedComponents(Graph G = Graph(0, true)){ int n = mn = G.numVertices(); int m = mm = G.numEdges(); mG = std::move(G); if(n == 0){ mnum_bcs = 0; return; } auto adj = mG.getAdjacencyArray(); auto dfstree = DfsTree::Construct(adj); std::vector vtxToDfsi(n), parent, low; for(int i=0; i=0; i--){ int p = dfstree.dfsOrd[i]; int pp = parent[p]; if(pp >= 0) low[pp] = std::min(low[pp], low[p]); } int num_bcs = 0; std::vector res(m); for(int p : dfstree.dfsOrd) if(parent[p] >= 0){ int pp = parent[p]; if(low[p] < vtxToDfsi[pp]){ low[p] = low[pp]; m_bcVtxPair.push_back(std::make_pair(low[p], p)); } else{ low[p] = num_bcs++; m_bcVtxPair.push_back(std::make_pair(low[p], pp)); m_bcVtxPair.push_back(std::make_pair(low[p], p)); } } for(int s=0; s getBcVertices() const { return CsrArray::Construct(numComponents(), m_bcVtxPair); } Graph getBcTree() const { int bct_n = mn + mnum_bcs; std::vector> res = m_bcVtxPair; for(auto& e : res) e.first += mn; return Graph(bct_n, std::move(res), true); } CsrArray getBcEdges() const { auto bct = getBcTree().getAdjacencyArray(); std::vector bfsP(bct.size(), -1); std::vector bfsD(bct.size(), 0); std::vector bfs(bct.size()); int p0 = 0, p1 = 0; for(int s=0; s> res(mm); for(int i=0; i::Construct(mnum_bcs, res); } }; } // namespace nachia #line 2 "nachia\\misc\\fastio.hpp" #include #include #include #include namespace nachia{ struct CInStream{ private: static const unsigned int INPUT_BUF_SIZE = 1 << 17; unsigned int p = INPUT_BUF_SIZE; static char Q[INPUT_BUF_SIZE]; public: using MyType = CInStream; char seekChar(){ if(p == INPUT_BUF_SIZE){ size_t len = fread(Q, 1, INPUT_BUF_SIZE, stdin); if(len != INPUT_BUF_SIZE) Q[len] = '\0'; p = 0; } return Q[p]; } void skipSpace(){ while(isspace(seekChar())) p++; } uint32_t nextU32(){ skipSpace(); uint32_t buf = 0; while(true){ char tmp = seekChar(); if('9' < tmp || tmp < '0') break; buf = buf * 10 + (tmp - '0'); p++; } return buf; } int32_t nextI32(){ skipSpace(); if(seekChar() == '-'){ p++; return (int32_t)(-nextU32()); } return (int32_t)nextU32(); } uint64_t nextU64(){ skipSpace(); uint64_t buf = 0; while(true){ char tmp = seekChar(); if('9' < tmp || tmp < '0') break; buf = buf * 10 + (tmp - '0'); p++; } return buf; } int64_t nextI64(){ skipSpace(); if(seekChar() == '-'){ p++; return (int64_t)(-nextU64()); } return (int64_t)nextU64(); } char nextChar(){ skipSpace(); char buf = seekChar(); p++; return buf; } std::string nextToken(){ skipSpace(); std::string buf; while(true){ char ch = seekChar(); if(isspace(ch) || ch == '\0') break; buf.push_back(ch); p++; } return buf; } MyType& operator>>(unsigned int& dest){ dest = nextU32(); return *this; } MyType& operator>>(int& dest){ dest = nextI32(); return *this; } MyType& operator>>(unsigned long& dest){ dest = nextU64(); return *this; } MyType& operator>>(long& dest){ dest = nextI64(); return *this; } MyType& operator>>(unsigned long long& dest){ dest = nextU64(); return *this; } MyType& operator>>(long long& dest){ dest = nextI64(); return *this; } MyType& operator>>(std::string& dest){ dest = nextToken(); return *this; } MyType& operator>>(char& dest){ dest = nextChar(); return *this; } } cin; struct FastOutputTable{ char LZ[1000][4] = {}; char NLZ[1000][4] = {}; constexpr FastOutputTable(){ using u32 = uint_fast32_t; for(u32 d=0; d<1000; d++){ LZ[d][0] = ('0' + d / 100 % 10); LZ[d][1] = ('0' + d / 10 % 10); LZ[d][2] = ('0' + d / 1 % 10); LZ[d][3] = '\0'; } for(u32 d=0; d<1000; d++){ u32 i = 0; if(d >= 100) NLZ[d][i++] = ('0' + d / 100 % 10); if(d >= 10) NLZ[d][i++] = ('0' + d / 10 % 10); if(d >= 1) NLZ[d][i++] = ('0' + d / 1 % 10); NLZ[d][i++] = '\0'; } } }; struct COutStream{ private: using u32 = uint32_t; using u64 = uint64_t; using MyType = COutStream; static const u32 OUTPUT_BUF_SIZE = 1 << 17; static char Q[OUTPUT_BUF_SIZE]; static constexpr FastOutputTable TB = FastOutputTable(); u32 p = 0; static constexpr u32 P10(u32 d){ return d ? P10(d-1)*10 : 1; } static constexpr u64 P10L(u32 d){ return d ? P10L(d-1)*10 : 1; } template static void Fil(T& m, U& l, U x) noexcept { m = l/x; l -= m*x; } void next_dig9(u32 x){ u32 y; Fil(y, x, P10(6)); nextCstr(TB.LZ[y]); Fil(y, x, P10(3)); nextCstr(TB.LZ[y]); nextCstr(TB.LZ[x]); } public: void nextChar(char c){ Q[p++] = c; if(p == OUTPUT_BUF_SIZE){ fwrite(Q, p, 1, stdout); p = 0; } } void nextEoln(){ nextChar('\n'); } void nextCstr(const char* s){ while(*s) nextChar(*(s++)); } void nextU32(uint32_t x){ u32 y = 0; if(x >= P10(9)){ Fil(y, x, P10(9)); nextCstr(TB.NLZ[y]); next_dig9(x); } else if(x >= P10(6)){ Fil(y, x, P10(6)); nextCstr(TB.NLZ[y]); Fil(y, x, P10(3)); nextCstr(TB.LZ[y]); nextCstr(TB.LZ[x]); } else if(x >= P10(3)){ Fil(y, x, P10(3)); nextCstr(TB.NLZ[y]); nextCstr(TB.LZ[x]); } else if(x >= 1) nextCstr(TB.NLZ[x]); else nextChar('0'); } void nextI32(int32_t x){ if(x >= 0) nextU32(x); else{ nextChar('-'); nextU32((u32)-x); } } void nextU64(uint64_t x){ u32 y = 0; if(x >= P10L(18)){ Fil(y, x, P10L(18)); nextU32(y); Fil(y, x, P10L(9)); next_dig9(y); next_dig9(x); } else if(x >= P10L(9)){ Fil(y, x, P10L(9)); nextU32(y); next_dig9(x); } else nextU32(x); } void nextI64(int64_t x){ if(x >= 0) nextU64(x); else{ nextChar('-'); nextU64((u64)-x); } } void writeToFile(bool flush = false){ fwrite(Q, p, 1, stdout); if(flush) fflush(stdout); p = 0; } COutStream(){ Q[0] = 0; } ~COutStream(){ writeToFile(); } MyType& operator<<(unsigned int tg){ nextU32(tg); return *this; } MyType& operator<<(unsigned long tg){ nextU64(tg); return *this; } MyType& operator<<(unsigned long long tg){ nextU64(tg); return *this; } MyType& operator<<(int tg){ nextI32(tg); return *this; } MyType& operator<<(long tg){ nextI64(tg); return *this; } MyType& operator<<(long long tg){ nextI64(tg); return *this; } MyType& operator<<(const std::string& tg){ nextCstr(tg.c_str()); return *this; } MyType& operator<<(const char* tg){ nextCstr(tg); return *this; } MyType& operator<<(char tg){ nextChar(tg); return *this; } } cout; char CInStream::Q[INPUT_BUF_SIZE]; char COutStream::Q[OUTPUT_BUF_SIZE]; } // namespace nachia #line 6 "Main.cpp" #define rep(i,n) for(int i=0; i<(int)(n); i++) int main() { using nachia::cin, nachia::cout; int n; cin >> n; int m; cin >> m; nachia::Graph G(n, true); for(int i=0; i> u >> v; G.addEdge(u-1, v-1); } auto hld_bct = nachia::HeavyLightDecomposition(nachia::BiconnectedComponents(G).getBcTree().getAdjacencyArray()); 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; }