#include<bits/stdc++.h> using namespace std; #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace __gnu_pbds; typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set; typedef long long ll; typedef pair<ll,ll> pll; typedef pair<ll,int> pli; typedef pair<int,ll> pil; typedef pair<int,int> pii; const ll INFLL=1e18+7; const int INF=1e9+7; #define pb push_back const int MAXN=3e3+7; int arr[MAXN]; int pos[MAXN]; int n; bool check(){ for(int i=1;i<n;++i) if(arr[i]>arr[i+1]) return 0; return 1; } bool visited[MAXN]; int main() { ios_base::sync_with_stdio(0); cin>>n; for(int i=1;i<=n;++i) cin>>arr[i]; vector<pii> scalar; for(int i=1;i<=n;++i) scalar.pb({arr[i],i}); sort(scalar.begin(),scalar.end()); for(int i=0;i<n;++i) arr[scalar[i].second]=i+1; for(int i=1;i<=n;++i) pos[arr[i]]=i; if(check()){ cout<<"0\n"; return 0; } vector<int> round1,round_ba; for(int i=1;i<=n;++i){ if(visited[arr[i]]) continue; int x=arr[i]; vector<int> cycle; visited[arr[i]]=1; cycle.pb(arr[i]); while(arr[x]!=arr[i]){ x=arr[x]; visited[x]=1; cycle.pb(x); } for(int j=0;j<(int)cycle.size()/2;++j){ round1.pb(pos[cycle[j]]); round_ba.pb(pos[cycle[(int)cycle.size()-j-1]]); swap(arr[pos[cycle[j]]],arr[pos[cycle[(int)cycle.size()-j-1]]]); } //~ for(int &v:cycle) cout<<v<<" "; //~ cout<<"\n"; } reverse(round_ba.begin(),round_ba.end()); for(int &v:round_ba) round1.pb(v); if(check()){ cout<<"1\n"; cout<<(int)round1.size()<<"\n"; for(int &v:round1) cout<<v<<" "; cout<<"\n"; return 0; } //~ cout<<"*******\n"; //~ for(int i=1;i<=n;++i) cout<<arr[i]<<" "; //~ cout<<"\n"; for(int i=1;i<=n;++i) pos[arr[i]]=i; vector<int> round2,round2_ba; for(int i=1;i<=n;++i){ if(arr[i]==i) continue; //~ cout<<arr[i]<<" "<<arr[arr[i]]<<"~\n"; round2.pb(i); round2_ba.pb(arr[i]); swap(arr[i],arr[arr[i]]); } reverse(round2_ba.begin(),round2_ba.end()); for(int &v:round2_ba) round2.pb(v); cout<<"2\n"; cout<<(int)round1.size()<<"\n"; for(int &v:round1) cout<<v<<" "; cout<<"\n"; cout<<(int)round2.size()<<"\n"; for(int &v:round2) cout<<v<<" "; cout<<"\n"; //~ for(int i=1;i<=n;++i) cout<<arr[i]<<" "; //~ cout<<"\n"; }
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 | #include<bits/stdc++.h> using namespace std; #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace __gnu_pbds; typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set; typedef long long ll; typedef pair<ll,ll> pll; typedef pair<ll,int> pli; typedef pair<int,ll> pil; typedef pair<int,int> pii; const ll INFLL=1e18+7; const int INF=1e9+7; #define pb push_back const int MAXN=3e3+7; int arr[MAXN]; int pos[MAXN]; int n; bool check(){ for(int i=1;i<n;++i) if(arr[i]>arr[i+1]) return 0; return 1; } bool visited[MAXN]; int main() { ios_base::sync_with_stdio(0); cin>>n; for(int i=1;i<=n;++i) cin>>arr[i]; vector<pii> scalar; for(int i=1;i<=n;++i) scalar.pb({arr[i],i}); sort(scalar.begin(),scalar.end()); for(int i=0;i<n;++i) arr[scalar[i].second]=i+1; for(int i=1;i<=n;++i) pos[arr[i]]=i; if(check()){ cout<<"0\n"; return 0; } vector<int> round1,round_ba; for(int i=1;i<=n;++i){ if(visited[arr[i]]) continue; int x=arr[i]; vector<int> cycle; visited[arr[i]]=1; cycle.pb(arr[i]); while(arr[x]!=arr[i]){ x=arr[x]; visited[x]=1; cycle.pb(x); } for(int j=0;j<(int)cycle.size()/2;++j){ round1.pb(pos[cycle[j]]); round_ba.pb(pos[cycle[(int)cycle.size()-j-1]]); swap(arr[pos[cycle[j]]],arr[pos[cycle[(int)cycle.size()-j-1]]]); } //~ for(int &v:cycle) cout<<v<<" "; //~ cout<<"\n"; } reverse(round_ba.begin(),round_ba.end()); for(int &v:round_ba) round1.pb(v); if(check()){ cout<<"1\n"; cout<<(int)round1.size()<<"\n"; for(int &v:round1) cout<<v<<" "; cout<<"\n"; return 0; } //~ cout<<"*******\n"; //~ for(int i=1;i<=n;++i) cout<<arr[i]<<" "; //~ cout<<"\n"; for(int i=1;i<=n;++i) pos[arr[i]]=i; vector<int> round2,round2_ba; for(int i=1;i<=n;++i){ if(arr[i]==i) continue; //~ cout<<arr[i]<<" "<<arr[arr[i]]<<"~\n"; round2.pb(i); round2_ba.pb(arr[i]); swap(arr[i],arr[arr[i]]); } reverse(round2_ba.begin(),round2_ba.end()); for(int &v:round2_ba) round2.pb(v); cout<<"2\n"; cout<<(int)round1.size()<<"\n"; for(int &v:round1) cout<<v<<" "; cout<<"\n"; cout<<(int)round2.size()<<"\n"; for(int &v:round2) cout<<v<<" "; cout<<"\n"; //~ for(int i=1;i<=n;++i) cout<<arr[i]<<" "; //~ cout<<"\n"; } |