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  1.     #include <algorithm>
  2.     #include <vector>
  3.     #include <iterator>
  4.     #include <set>
  5.     #include <iostream>
  6.     #include <numeric>
  7.  
  8.     using namespace std;
  9.  
  10.     int main()
  11.     {
  12.         std::vector<int> L = { 1, 2, 4, 3, 2, 4 };
  13.         std::set<int> tempSet;
  14.         //...
  15.         // partition the elements, unique items on left, duplicates on right
  16.         auto divider = stable_partition(L.begin(), L.end(), [&](int n)
  17.         {
  18.             // return true if item is not in the set, false otherwise
  19.             return tempSet.insert(n).second;
  20.         });
  21.  
  22.         // do something with the duplicates, for example, print them
  23.         cout << "Here are the dups:\n";
  24.         copy(divider, L.end(), ostream_iterator<int>(cout, " "));
  25.  
  26.         // get the average
  27.  
  28.         // get number of duplicates  
  29.         size_t numDups = std::distance(divider, L.end());  
  30.         double avg = 0.0;
  31.  
  32.         // compute average using std::accumulate
  33.         if ( numDups > 0 ) 
  34.            avg = std::accumulate(divider, L.end(), 0.0) / numDups;
  35.         cout << "\nThe average of the duplicates is: " << avg << "\n";
  36.  
  37.         // erase the duplicates
  38.         L.erase(divider, L.end());
  39.  
  40.         // print the updated vector now
  41.         cout << "\n\nHere is the resulting vector:\n";
  42.         copy(L.begin(), L.end(), ostream_iterator<int>(cout, " "));
  43.     }
  44.  
Success #stdin #stdout 0s 3464KB
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stdin
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Standard input is empty
stdout
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Here are the dups:
2 4 
The average of the duplicates is: 3


Here is the resulting vector:
1 2 4 3
https://ideone.com/P0o7kb
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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