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  1. #include <iostream>
  2. #include <vector>
  3. using namespace std;
  4.  
  5. int calculateSum(const std::vector<int> &vec)
  6. {
  7. int result{0};
  8. bool addPlus = false;
  9.  
  10. for (size_t i = 0; i < vec.size(); ++i) {
  11. for (size_t j = i + 1; j < vec.size(); ++j) {
  12. if (addPlus) cout << "+ "; else addPlus = true;
  13. cout << "{" << vec[i] << " * " << vec[j] << "} ";
  14. result += vec[i] * vec[j];
  15. }
  16. }
  17.  
  18. cout << "= " << result << endl;
  19. return result;
  20. }
  21.  
  22.  
  23. int main() {
  24. calculateSum({});
  25. cout << endl;
  26. calculateSum({1});
  27. cout << endl;
  28. calculateSum({1, 2});
  29. cout << endl;
  30. calculateSum({1, 2, 3});
  31. return 0;
  32. }
Success #stdin #stdout 0.01s 5568KB
stdin
Standard input is empty
stdout
= 0

= 0

{1 * 2} = 2

{1 * 2} + {1 * 3} + {2 * 3} = 11