Submission #861274

#	Time	Username	Problem	Language	Result	Execution time	Memory
861274		Ahmed57	Cat (info1cup19_cat)	C++17	0 / 100	1066 ms	4828 KiB

cat

#include <bits/stdc++.h>

using namespace std;
vector<pair<int,int>> con;
int vis[200001],arr[200001];
void dfs(int i,int st){
    if(st!=i)con.push_back({st,i});
    vis[i] = 1;
    if(vis[arr[i]]==0)dfs(arr[i],st);
}
int main(){
    int t;cin>>t;
    z:while(t--){
        int n;cin>>n;
        for(int i = 1;i<=n;i++)vis[i] = 0;
        int pos[n+1];
        for(int i = 1;i<=n;i++){
            cin>>arr[i];pos[arr[i]] = i;
        }
        int g = 0;int lol = 0;
        for(int i = 1;i<=n/2;i++){
            if(arr[i]!=i)g++;
            if(n-arr[i]+1!=arr[n-i+1]){
                cout<<-1<<endl;
                goto z;
            }if(arr[i]>n/2){
                lol++;
            }
        }
        if(lol&1){
            cout<<-1<<endl;
            goto z;
        }
        for(int i = 1;i<=n/2;i++){
            if(!vis[i])dfs(i,i);
        }
        cout<<con.size()<<" "<<con.size()<<endl;
        for(auto i:con)cout<<i.first<<" "<<i.second<<endl;
    }
}

Compilation message (stderr)

cat.cpp: In function 'int main()':
cat.cpp:16:13: warning: variable 'pos' set but not used [-Wunused-but-set-variable]
   16 |         int pos[n+1];
      |             ^~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 15
• Subtask 5: 0 / 35