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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define pb emplace_back
  4.  
  5. int main()
  6. {
  7.  
  8.   int t = 1;
  9.   cin >> t;
  10.   while (t--)
  11.   {
  12.  
  13.     int n, i, x, ok = 0;
  14.     cin >> n;
  15.  
  16.     multiset<int> s;
  17.  
  18.     for (i = 0; i < n; i++)
  19.     {
  20.       cin >> x;
  21.       s.insert(x);
  22.     }
  23.  
  24.     int op = 0;
  25.  
  26.     for (i = 1; i <= n; i++)
  27.     {
  28.       if (s.find(i) != s.end())
  29.         s.erase(s.find(i));
  30.  
  31.       else
  32.       {
  33.         auto it = s.begin();
  34.         x = *it;
  35.  
  36.         if (x < i)
  37.           op++;
  38.  
  39.         else
  40.         {
  41.           ok = 1;
  42.           break;
  43.         }
  44.  
  45.         s.erase(it);
  46.       }
  47.     }
  48.  
  49.     if (ok == 1)
  50.       op = -1;
  51.  
  52.     cout << op << endl;
  53.  
  54.  
  55.   }
  56. }
Success #stdin #stdout 0s 5660KB
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stdout
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https://ideone.com/J0zm4b
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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