#include <bits/stdc++.h> using namespace std; const int N = 3001; int n, t[N]; vector<int> v[2], tmp; vector<pair<int, int>> sortv; int q; bool w[N]; bool red() { bool ok = true; sort(sortv.begin(), sortv.end()); for (int i = 0; i < n; i++) { int p = sortv[i].second; t[p] = i; if (t[i] != i) { ok = false; } } return ok; } int main() { ios_base::sync_with_stdio(0); cin >> n; for (int i = 0; i < n; i++) { cin >> t[i]; sortv.push_back(make_pair(t[i], i)); } bool ok = red(); if (ok) { cout << 0 << endl; return 0; } fill(w, w + n, false); for (int i = 0; i < n; i++) { if (w[i]) { continue; } int l = 0, a = i; do { w[a] = true; a = t[a]; l++; } while (a != i); if (l == 2) { v[0].push_back(i); v[1].push_back(t[i]); } if (l <= 2) { continue; } int pary = (l - 1) / 2; a = t[a]; for (int x = 0; x < pary; x++) { v[0].push_back(a); a = t[a]; } if (l % 2 == 0) { a = t[a]; } for (int x = 0; x < pary; x++) { tmp.push_back(a); a = t[a]; } while(!tmp.empty()) { v[1].push_back(tmp.back()); tmp.pop_back(); } } for (int i = 0; i < v[0].size(); i++) { swap(t[v[0][i]], t[v[1][i]]); } int q = 0; for (int i = 0; i < n; i++) { if (t[i] != i) { q++; } } if (q == 0) { cout << "1" << endl; } else { cout << "2" << endl; } cout << v[0].size() + v[1].size() << endl; for (int i = 0; i < v[0].size(); i++) { cout << v[0][i] + 1 << " "; } while (!v[1].empty()) { cout << v[1].back() + 1 << " "; v[1].pop_back(); } cout << endl; if (q > 0) { cout << q << endl; for (int i = 0; i < n; i++) { if (t[i] != i) { cout << i + 1 << " "; v[1].push_back(t[i]); swap(t[t[i]], t[i]); } } while (!v[1].empty()) { cout << v[1].back() + 1 << " "; v[1].pop_back(); } cout << 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 | #include <bits/stdc++.h> using namespace std; const int N = 3001; int n, t[N]; vector<int> v[2], tmp; vector<pair<int, int>> sortv; int q; bool w[N]; bool red() { bool ok = true; sort(sortv.begin(), sortv.end()); for (int i = 0; i < n; i++) { int p = sortv[i].second; t[p] = i; if (t[i] != i) { ok = false; } } return ok; } int main() { ios_base::sync_with_stdio(0); cin >> n; for (int i = 0; i < n; i++) { cin >> t[i]; sortv.push_back(make_pair(t[i], i)); } bool ok = red(); if (ok) { cout << 0 << endl; return 0; } fill(w, w + n, false); for (int i = 0; i < n; i++) { if (w[i]) { continue; } int l = 0, a = i; do { w[a] = true; a = t[a]; l++; } while (a != i); if (l == 2) { v[0].push_back(i); v[1].push_back(t[i]); } if (l <= 2) { continue; } int pary = (l - 1) / 2; a = t[a]; for (int x = 0; x < pary; x++) { v[0].push_back(a); a = t[a]; } if (l % 2 == 0) { a = t[a]; } for (int x = 0; x < pary; x++) { tmp.push_back(a); a = t[a]; } while(!tmp.empty()) { v[1].push_back(tmp.back()); tmp.pop_back(); } } for (int i = 0; i < v[0].size(); i++) { swap(t[v[0][i]], t[v[1][i]]); } int q = 0; for (int i = 0; i < n; i++) { if (t[i] != i) { q++; } } if (q == 0) { cout << "1" << endl; } else { cout << "2" << endl; } cout << v[0].size() + v[1].size() << endl; for (int i = 0; i < v[0].size(); i++) { cout << v[0][i] + 1 << " "; } while (!v[1].empty()) { cout << v[1].back() + 1 << " "; v[1].pop_back(); } cout << endl; if (q > 0) { cout << q << endl; for (int i = 0; i < n; i++) { if (t[i] != i) { cout << i + 1 << " "; v[1].push_back(t[i]); swap(t[t[i]], t[i]); } } while (!v[1].empty()) { cout << v[1].back() + 1 << " "; v[1].pop_back(); } cout << endl; } return 0; } |