#include <iostream> #include <vector> #include <algorithm> using namespace std; const long long int VV=500*1000+7; const long long int XX=VV+7; vector<int> graf[VV]; int N, dek[VV], tab[VV], v, e, minskok[VV], minn, maxx, wyn, dokiedynie; char kol[VV]; bool czy, wypisz[VV]; int lsas(int ii) {return (graf[ii].size());} int isas(int ii, int iii) {return (graf[ii][iii]);} void DFS1(int w) { int j; dek[w] = XX + 1; for (j = 0; j < lsas(w); j++) if (dek[isas(w, j)] == XX) DFS1(isas(w, j)); dek[w] = N; tab[N] = w; N--; return; } int DFS2(int w) { int i, j; int ret = XX; kol[w] = 's'; for (j = 0; j < lsas(w); j++) { i = isas(w, j); if (kol[i] == 's') { minn = max(minn, dek[i]); maxx = min(maxx, dek[w]); ret = min(ret, dek[i]); czy = true; } else if (kol[i] == 'b') { minskok[i] = DFS2(i); ret = min(ret, minskok[i]); } else if (kol[i] == 'c') ret = min(ret, minskok[i]); } kol[w] = 'c'; return ret; } int i, j, k; int main() { ios_base::sync_with_stdio(0); cin >> v >> e; for (i = 0; i < e; i++) { cin >> j >> k; graf[j].push_back(k); } N = v; minn = 1; maxx = v; wyn = 0; czy = false; dokiedynie = 0; for (i = 1; i < v + 1; i++) { dek[i] = XX; kol[i] = 'b'; minskok[i] = XX; wypisz[i] = false; } for (i = 1; i < v + 1; i++) if (dek[i] == XX) DFS1(i); for (i = 1; i < v + 1; i++) if (kol[i] == 'b') minskok[i] = DFS2(i); if (czy == false) cout << "NIE"; else if (minn > maxx) cout << 0 << "\n"; else { for (i = 1; i < maxx + 1; i++) { if (i >= minn) { wypisz[tab[i]] = true; wyn++; } for (k = 0; k < lsas(tab[i]); k++) { j = isas(tab[i], k); if (dek[j] > i + 1) if (minskok[j] <= i) minn = max(minn, dek[j]); } } cout << wyn << "\n"; for (i = 1; i < v + 1; i++) if (wypisz[i] == true) cout << i << " "; } /* cout << "tab: \n"; for (i = 1; i < v + 1; i++) cout << tab[i] << " "; cout << "\n"; cout << "minskok: \n"; for (i = 1; i < v + 1; i++) cout << minskok[i] << " "; cout << "\n"; cout << "minn, maxx: " << minn << ", " << maxx << "\n";*/ 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 | #include <iostream> #include <vector> #include <algorithm> using namespace std; const long long int VV=500*1000+7; const long long int XX=VV+7; vector<int> graf[VV]; int N, dek[VV], tab[VV], v, e, minskok[VV], minn, maxx, wyn, dokiedynie; char kol[VV]; bool czy, wypisz[VV]; int lsas(int ii) {return (graf[ii].size());} int isas(int ii, int iii) {return (graf[ii][iii]);} void DFS1(int w) { int j; dek[w] = XX + 1; for (j = 0; j < lsas(w); j++) if (dek[isas(w, j)] == XX) DFS1(isas(w, j)); dek[w] = N; tab[N] = w; N--; return; } int DFS2(int w) { int i, j; int ret = XX; kol[w] = 's'; for (j = 0; j < lsas(w); j++) { i = isas(w, j); if (kol[i] == 's') { minn = max(minn, dek[i]); maxx = min(maxx, dek[w]); ret = min(ret, dek[i]); czy = true; } else if (kol[i] == 'b') { minskok[i] = DFS2(i); ret = min(ret, minskok[i]); } else if (kol[i] == 'c') ret = min(ret, minskok[i]); } kol[w] = 'c'; return ret; } int i, j, k; int main() { ios_base::sync_with_stdio(0); cin >> v >> e; for (i = 0; i < e; i++) { cin >> j >> k; graf[j].push_back(k); } N = v; minn = 1; maxx = v; wyn = 0; czy = false; dokiedynie = 0; for (i = 1; i < v + 1; i++) { dek[i] = XX; kol[i] = 'b'; minskok[i] = XX; wypisz[i] = false; } for (i = 1; i < v + 1; i++) if (dek[i] == XX) DFS1(i); for (i = 1; i < v + 1; i++) if (kol[i] == 'b') minskok[i] = DFS2(i); if (czy == false) cout << "NIE"; else if (minn > maxx) cout << 0 << "\n"; else { for (i = 1; i < maxx + 1; i++) { if (i >= minn) { wypisz[tab[i]] = true; wyn++; } for (k = 0; k < lsas(tab[i]); k++) { j = isas(tab[i], k); if (dek[j] > i + 1) if (minskok[j] <= i) minn = max(minn, dek[j]); } } cout << wyn << "\n"; for (i = 1; i < v + 1; i++) if (wypisz[i] == true) cout << i << " "; } /* cout << "tab: \n"; for (i = 1; i < v + 1; i++) cout << tab[i] << " "; cout << "\n"; cout << "minskok: \n"; for (i = 1; i < v + 1; i++) cout << minskok[i] << " "; cout << "\n"; cout << "minn, maxx: " << minn << ", " << maxx << "\n";*/ return 0; } |