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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. struct MyOwnClass { int score; };
  6.  
  7. std::size_t get_index_of_nth_greatest(const std::vector<MyOwnClass>& v, std::size_t k)
  8. {
  9.     std::vector<std::size_t> indexes(v.size());
  10.     std::iota(indexes.begin(), indexes.end(), 0);
  11.  
  12.     std::nth_element(indexes.begin(), indexes.begin() + k, indexes.end(),
  13.         [&](int lhs, int rhs)
  14.         {
  15.             return v[lhs].score > v[rhs].score;
  16.         }
  17.     );
  18.     return indexes[k];
  19. }
  20.  
  21.  
  22. int main()
  23. {
  24.     std::vector<MyOwnClass> scores = {{2}, {42}, {5}, {21}, {1}, {3}};
  25.  
  26.     for (std::size_t i = 0; i != scores.size(); ++i) {
  27.         const auto index = get_index_of_nth_greatest(scores, i);
  28.         std::cout << i << "th greater is at index " << index
  29.             << " with value " << scores[index].score << std::endl;
  30.     }
  31. }
  32.  
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
stdout
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0th greater is at index 1 with value 42
1th greater is at index 3 with value 21
2th greater is at index 2 with value 5
3th greater is at index 5 with value 3
4th greater is at index 0 with value 2
5th greater is at index 4 with value 1
https://ideone.com/2chePe
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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