#include <cstdlib> #include <stdio.h> #include <iostream> #include <vector> #include <set> #include <map> #include <queue> #include <algorithm> #include <list> #include <iterator> using namespace std; typedef vector< list<size_t> > AdjListT; AdjListT A, B; vector<size_t> node_stack; vector<size_t> blocked; size_t s; int ile_cykli = 0; void UNBLOCK(size_t); bool CIRCUIT(size_t); void OutputCycle(vector<size_t>&); bool CIRCUIT(size_t v) { if (ile_cykli>5) return false; bool f = false; node_stack.push_back(v); blocked[v] = true; for (list<size_t>::iterator iw = A[v].begin(); iw != A[v].end(); ++iw) { size_t w = *iw; if (w == s) { OutputCycle(node_stack); f = true; } else if (!blocked[w]) { if (CIRCUIT(w)) f = true; } } if (f) UNBLOCK(v); else for (list<size_t>::iterator iw = A[v].begin(); iw != A[v].end(); ++iw) { size_t w = *iw; if (find(B[w].begin(), B[w].end(), v) == B[w].end()) B[w].push_back(v); } node_stack.pop_back(); return f; } void UNBLOCK(size_t u) { blocked[u] = false; for (list<size_t>::iterator iw = B[u].begin(); iw != B[u].end();) { size_t w = *iw; iw = B[u].erase(iw); if (blocked[w]) UNBLOCK(w); } return; } vector< set<int> const* > sety = vector< set<int> const* >(); void OutputCycle(vector<size_t>& node_stack) { set<int> *newset = new set<int>(); for (vector<size_t>::iterator i = node_stack.begin(); i != node_stack.end(); ++i) { // cout << *i << " "; newset->insert(*i); } ile_cykli++; sety.push_back(newset); // cout << endl; return; } std::vector<int> intersect(vector< set<int> const* > const& sets) { std::vector<int> result; // only return this one, for NRVO to kick in // 0. Check obvious cases if (sets.empty()) { return result; } if (sets.size() == 1) { result.assign(sets.front()->begin(), sets.front()->end()); return result; } // 1. Merge first two sets in the result std::set_intersection(sets[0]->begin(), sets[0]->end(), sets[1]->begin(), sets[1]->end(), std::back_inserter(result)); if (sets.size() == 2) { return result; } // 2. Merge consecutive sets with result into buffer, then swap them around // so that the "result" is always in result at the end of the loop. std::vector<int> buffer; // outside the loop so that we reuse its memory for (size_t i = 2; i < sets.size(); ++i) { buffer.clear(); std::set_intersection(result.begin(), result.end(), sets[i]->begin(), sets[i]->end(), std::back_inserter(buffer)); swap(result, buffer); } return result; } int main() { std::ios_base::sync_with_stdio(0); size_t N, m; std::cin >> N >> m; A.resize(N+1); blocked.resize(N+1); B.resize(N+1); int u,v; for(int i=0;i<m;i++) { cin >> u >> v; A.at(u).push_back(v); } for (size_t i = 0; i <= N; ++i) blocked[i] = false; s = 0; while (s <= N) { CIRCUIT(s); ile_cykli=0; A[s].clear(); for (size_t i = 0; i < N; ++i) A[i].remove(s); for (size_t i = 0; i <= N; ++i) { blocked[i] = false; B[i].clear(); } ++s; } auto result = intersect(sety); if (sety.size()==0) { std::cout << "NIE" << std::endl; } else { std::cout << result.size() << std::endl; for (vector<int>::iterator i = result.begin(); i != result.end(); ++i) { cout << *i << " "; } } return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 | #include <cstdlib> #include <stdio.h> #include <iostream> #include <vector> #include <set> #include <map> #include <queue> #include <algorithm> #include <list> #include <iterator> using namespace std; typedef vector< list<size_t> > AdjListT; AdjListT A, B; vector<size_t> node_stack; vector<size_t> blocked; size_t s; int ile_cykli = 0; void UNBLOCK(size_t); bool CIRCUIT(size_t); void OutputCycle(vector<size_t>&); bool CIRCUIT(size_t v) { if (ile_cykli>5) return false; bool f = false; node_stack.push_back(v); blocked[v] = true; for (list<size_t>::iterator iw = A[v].begin(); iw != A[v].end(); ++iw) { size_t w = *iw; if (w == s) { OutputCycle(node_stack); f = true; } else if (!blocked[w]) { if (CIRCUIT(w)) f = true; } } if (f) UNBLOCK(v); else for (list<size_t>::iterator iw = A[v].begin(); iw != A[v].end(); ++iw) { size_t w = *iw; if (find(B[w].begin(), B[w].end(), v) == B[w].end()) B[w].push_back(v); } node_stack.pop_back(); return f; } void UNBLOCK(size_t u) { blocked[u] = false; for (list<size_t>::iterator iw = B[u].begin(); iw != B[u].end();) { size_t w = *iw; iw = B[u].erase(iw); if (blocked[w]) UNBLOCK(w); } return; } vector< set<int> const* > sety = vector< set<int> const* >(); void OutputCycle(vector<size_t>& node_stack) { set<int> *newset = new set<int>(); for (vector<size_t>::iterator i = node_stack.begin(); i != node_stack.end(); ++i) { // cout << *i << " "; newset->insert(*i); } ile_cykli++; sety.push_back(newset); // cout << endl; return; } std::vector<int> intersect(vector< set<int> const* > const& sets) { std::vector<int> result; // only return this one, for NRVO to kick in // 0. Check obvious cases if (sets.empty()) { return result; } if (sets.size() == 1) { result.assign(sets.front()->begin(), sets.front()->end()); return result; } // 1. Merge first two sets in the result std::set_intersection(sets[0]->begin(), sets[0]->end(), sets[1]->begin(), sets[1]->end(), std::back_inserter(result)); if (sets.size() == 2) { return result; } // 2. Merge consecutive sets with result into buffer, then swap them around // so that the "result" is always in result at the end of the loop. std::vector<int> buffer; // outside the loop so that we reuse its memory for (size_t i = 2; i < sets.size(); ++i) { buffer.clear(); std::set_intersection(result.begin(), result.end(), sets[i]->begin(), sets[i]->end(), std::back_inserter(buffer)); swap(result, buffer); } return result; } int main() { std::ios_base::sync_with_stdio(0); size_t N, m; std::cin >> N >> m; A.resize(N+1); blocked.resize(N+1); B.resize(N+1); int u,v; for(int i=0;i<m;i++) { cin >> u >> v; A.at(u).push_back(v); } for (size_t i = 0; i <= N; ++i) blocked[i] = false; s = 0; while (s <= N) { CIRCUIT(s); ile_cykli=0; A[s].clear(); for (size_t i = 0; i < N; ++i) A[i].remove(s); for (size_t i = 0; i <= N; ++i) { blocked[i] = false; B[i].clear(); } ++s; } auto result = intersect(sety); if (sety.size()==0) { std::cout << "NIE" << std::endl; } else { std::cout << result.size() << std::endl; for (vector<int>::iterator i = result.begin(); i != result.end(); ++i) { cout << *i << " "; } } return 0; } |