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  1. #include <bits/stdc++.h>
  2. #define int long long
  3. using namespace std;
  4.  
  5. void solve() {
  6.     int n;
  7.     cin >> n;
  8.    vector<int> v(n);
  9.    for(int i=0;i<n;i++){
  10.    		cin>>v[i];
  11.    }
  12.    int x=-1;
  13.    for(int i=0;i<n;i++){
  14.    		if(v[i]!=i){
  15.    			if(x==-1)x=(v[i]&v[v[i]]);
  16.    			else{
  17.    				if(x!=(v[i]&v[v[i]])){
  18.    					cout<<0<<endl;
  19.    					return;
  20.    				}
  21.    				x=(v[i]&v[v[i]]);
  22.    			}
  23.    			swap(v[i],v[v[i]]);
  24.  
  25.    		}
  26.    }
  27.    cout<<x<<endl;
  28.  
  29.  
  30. }
  31.  
  32. signed main() {
  33.     int t;
  34.     cin >> t;
  35.     while (t--) {
  36.         solve();
  37.     }
  38.     return 0;
  39. }
  40.  
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/GqgvpW
language:
C++ (gcc 8.3)
created:
9 days ago
visibility:
public

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