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  1. #include <algorithm>
  2. #include <iomanip>
  3. #include <iostream>
  4. #include <vector>
  5. #include <set>
  6. #include <numeric>
  7. #include <map>
  8. #include <unordered_map>
  9. #include <stack>
  10. #include <queue>
  11. using namespace std;
  12. #define all(a) a.begin(), a.end()
  13. #define ll long long
  14. #define fo(i,n) for (long long i = 0; i < n; i++)
  15. ll formula (ll a)
  16. {
  17.     return a*(a+1)/2;
  18. }
  19. ll check (ll n)
  20. {
  21.     return (n == 1 || n == 36 || n == 1225 || n == 41616 || n == 1413721 || n == 48024900 || n == 1631432881 || n == 55420693056);
  22. }
  23. int main()
  24. {
  25.     ll i,a,b,c,n;
  26.     ios_base::sync_with_stdio(false);
  27.     string input;
  28.     cin.tie(0); cout.tie(0);
  29.     cin >> i;
  30.     while (i--)
  31.     {
  32.         ll cnt = 0;
  33.         cin >> a;
  34.         n = formula(a);
  35.         if (check(n))
  36.         {
  37.             cout << -1 << '\n';
  38.         }
  39.         else
  40.         {
  41.             cout << 2 << ' ' << 1 << ' ';
  42.             for (int i = 3; i <= a; i++)
  43.             {
  44.                 if (i+1 <= a && check(formula(i+1)))
  45.                 {
  46.                     cout << i + 2 << ' ';
  47.                 }
  48.                 else if (check(formula(i-1)))
  49.                 {
  50.                     cout << i - 2 << ' ';
  51.                 }
  52.                 else
  53.                 {
  54.                     cout << i << ' ';
  55.                 }
  56.             }
  57.             cout << '\n';
  58.         }
  59.     }
  60. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/pUXW5T
language:
C++14 (gcc 8.3)
created:
9 days ago
visibility:
public

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