#include <map> #include <set> #include <unordered_set> #include <unordered_map> #include <vector> #include <iostream> #include <algorithm> struct AllSetsIterator { AllSetsIterator(size_t n) : n(n), s(0) {} void advance() { while (!cur.empty() && cur.back() >= int(n - (s - cur.size() + 1)) ) { cur.pop_back(); } if (cur.empty()) { ++s; if (done()) return; cur.push_back(0); } else { cur.back()++; } while (cur.size() < s) { cur.push_back(cur.back() + 1); } } bool done() { return s > n; } const std::vector<int> current() { return cur; } private: const size_t n; std::vector<int> cur; size_t s; }; void test() { /* AllSetsIterator it(7); while (!it.done()) { for (const auto& s : it.current()) { std::clog << s << " "; } std::clog << std::endl; it.advance(); } */ int edges = 0; std::unordered_map<int, std::unordered_set<int>> g; for (int i=1; i<=200000; ++i) { for (int j=0;j<1000; ++j) { int r = rand(); if (r % 107 == 0) { int node = r % 200001; if (i < node) { g[i].insert(node); ++edges; } } } } std::cout << 200000 << " " << edges << " d" << std::endl; for (const auto& d : g) { for (int i : d.second) { std::cout << d.first << " " << i << std::endl; } } } bool verify( const std::vector<std::vector<int>>& nb, const std::unordered_set<int>& choice, const int d, std::unordered_set<int> canVisit ) { if (canVisit.begin() == canVisit.end()) return false; int start = *canVisit.begin(); std::vector<int> toVisit(1, start); while (!toVisit.empty()) { int cur = toVisit.back(); toVisit.pop_back(); canVisit.erase(cur); int connectsTo = 0; for (int neighbor : nb[cur]) { if (choice.count(neighbor) > 0) ++connectsTo; if (canVisit.count(neighbor) > 0) toVisit.push_back(neighbor); } if (connectsTo < d) return false; } return canVisit.empty(); } int main() { //test(); return 0; size_t n,m,d; std::cin >> n >> m >> d; std::vector<std::vector<int>> nb(n+1); for (size_t i=0;i<m;++i) { int a,b; std::cin >> a >> b; nb[a].push_back(b); nb[b].push_back(a); } // sort by degree std::multimap<size_t,int> byDegree; for (size_t i=1; i<=n; ++i) { byDegree.insert(std::make_pair(nb[i].size(), i)); } // order of nodes to work std::vector<int> ord; ord.reserve(n); // set of applicable nodes (deg(i) >= 1) std::unordered_set<int> mask; for (const auto& p : byDegree) { ord.push_back(p.second); if (p.first >= d) { mask.insert(p.second); } } int firstOk = -1; for (size_t i=0; i<n; ++i) { if (nb[ord[i]].size() >= d) { firstOk = i; break; } } size_t possible = (firstOk < 0) ? 0 : (n - firstOk); if (possible < d) { std::cout << "NIE" << std::endl; return 0; } // verify each set? AllSetsIterator it (possible); while (!it.done()) { auto usedMask = mask; for (int i : it.current()) { usedMask.erase(ord[firstOk + i]); } // sets smaller than d cannot assure d connectivity if (usedMask.size() < d) break; if (verify(nb, mask, d, usedMask)) { std::cout << usedMask.size() << std::endl; std::vector<int> sorted(usedMask.begin(), usedMask.end()); std::sort(sorted.begin(), sorted.end()); for (size_t i=0; i<sorted.size(); ++i) { std::cout << sorted[i] << " "; } std::cout << std::endl; return 0; } it.advance(); } std::cout << "NIE" << std::endl; 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 | #include <map> #include <set> #include <unordered_set> #include <unordered_map> #include <vector> #include <iostream> #include <algorithm> struct AllSetsIterator { AllSetsIterator(size_t n) : n(n), s(0) {} void advance() { while (!cur.empty() && cur.back() >= int(n - (s - cur.size() + 1)) ) { cur.pop_back(); } if (cur.empty()) { ++s; if (done()) return; cur.push_back(0); } else { cur.back()++; } while (cur.size() < s) { cur.push_back(cur.back() + 1); } } bool done() { return s > n; } const std::vector<int> current() { return cur; } private: const size_t n; std::vector<int> cur; size_t s; }; void test() { /* AllSetsIterator it(7); while (!it.done()) { for (const auto& s : it.current()) { std::clog << s << " "; } std::clog << std::endl; it.advance(); } */ int edges = 0; std::unordered_map<int, std::unordered_set<int>> g; for (int i=1; i<=200000; ++i) { for (int j=0;j<1000; ++j) { int r = rand(); if (r % 107 == 0) { int node = r % 200001; if (i < node) { g[i].insert(node); ++edges; } } } } std::cout << 200000 << " " << edges << " d" << std::endl; for (const auto& d : g) { for (int i : d.second) { std::cout << d.first << " " << i << std::endl; } } } bool verify( const std::vector<std::vector<int>>& nb, const std::unordered_set<int>& choice, const int d, std::unordered_set<int> canVisit ) { if (canVisit.begin() == canVisit.end()) return false; int start = *canVisit.begin(); std::vector<int> toVisit(1, start); while (!toVisit.empty()) { int cur = toVisit.back(); toVisit.pop_back(); canVisit.erase(cur); int connectsTo = 0; for (int neighbor : nb[cur]) { if (choice.count(neighbor) > 0) ++connectsTo; if (canVisit.count(neighbor) > 0) toVisit.push_back(neighbor); } if (connectsTo < d) return false; } return canVisit.empty(); } int main() { //test(); return 0; size_t n,m,d; std::cin >> n >> m >> d; std::vector<std::vector<int>> nb(n+1); for (size_t i=0;i<m;++i) { int a,b; std::cin >> a >> b; nb[a].push_back(b); nb[b].push_back(a); } // sort by degree std::multimap<size_t,int> byDegree; for (size_t i=1; i<=n; ++i) { byDegree.insert(std::make_pair(nb[i].size(), i)); } // order of nodes to work std::vector<int> ord; ord.reserve(n); // set of applicable nodes (deg(i) >= 1) std::unordered_set<int> mask; for (const auto& p : byDegree) { ord.push_back(p.second); if (p.first >= d) { mask.insert(p.second); } } int firstOk = -1; for (size_t i=0; i<n; ++i) { if (nb[ord[i]].size() >= d) { firstOk = i; break; } } size_t possible = (firstOk < 0) ? 0 : (n - firstOk); if (possible < d) { std::cout << "NIE" << std::endl; return 0; } // verify each set? AllSetsIterator it (possible); while (!it.done()) { auto usedMask = mask; for (int i : it.current()) { usedMask.erase(ord[firstOk + i]); } // sets smaller than d cannot assure d connectivity if (usedMask.size() < d) break; if (verify(nb, mask, d, usedMask)) { std::cout << usedMask.size() << std::endl; std::vector<int> sorted(usedMask.begin(), usedMask.end()); std::sort(sorted.begin(), sorted.end()); for (size_t i=0; i<sorted.size(); ++i) { std::cout << sorted[i] << " "; } std::cout << std::endl; return 0; } it.advance(); } std::cout << "NIE" << std::endl; return 0; } |