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  1. #include <string>
  2. #include <iostream>
  3. #include <vector>
  4. #include <algorithm>
  5. #include <iterator>
  6.  
  7. using namespace std;
  8.  
  9. typedef std::vector<int> ivec;
  10.  
  11. template <class T> bool flag_delete(pair<T,int> a) { return (a.second == 1); }
  12.  
  13. template <class T> void fun_delete_by_flag(vector<T> &vec_data, const ivec &vec_flag)
  14. {
  15. 	size_t n = vec_data.size();
  16. 	vector< pair<T,int> > vec;
  17. 	vec.reserve(n);
  18. 	for ( size_t i = 0; i < n; i += 1 ) 
  19. 		vec.push_back(std::make_pair(vec_data[i], vec_flag[i]));
  20.  
  21. 	auto it = remove_if(vec.begin(), vec.end(), flag_delete<T>);
  22. 	vec.erase(it);
  23.  
  24. 	n = vec.size();
  25. 	vec_data.resize(n);
  26.  
  27. 	for ( size_t i = 0; i < n; i += 1 )
  28. 		vec_data[i] = vec[i].first;
  29.  
  30. 	return;
  31. }
  32.  
  33. template <class T> void simpler(vector<T> &vec_data, const ivec &vec_flag)
  34. {
  35. 	T *begin = &vec_data.front();
  36. 	size_t newsize = std::distance(begin, 
  37. 			std::remove_if(
  38. 				begin, begin + vec_data.size(), [&] (T& el) 
  39. 				{ 
  40. 					return 1 == vec_flag[std::distance(begin, &el)]; 
  41.                                         // or maybe: return vec_flag[&el-begin];
  42. 				}));
  43.  
  44. 	vec_data.resize(newsize);
  45. }
  46.  
  47. int main()
  48. { 
  49. 	vector<std::string> data = { "hello", "world" };
  50. 	vector<int> flags = { 0, 1 };
  51.  
  52. 	std::cout << "BEFORE: "; std::copy(data.begin(), data.end(), std::ostream_iterator<std::string>(std::cout, ", ")); std::cout << "\n";
  53. 	fun_delete_by_flag(data, flags);
  54. 	// simpler(data, flags);
  55. 	std::cout << "AFTER:  "; std::copy(data.begin(), data.end(), std::ostream_iterator<std::string>(std::cout, ", ")); std::cout << "\n";
  56. }
  57.  
Success #stdin #stdout 0s 2968KB
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stdin
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Standard input is empty
stdout
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BEFORE: hello, world, 
AFTER:  hello,
https://ideone.com/S2WUC
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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