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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. int main() {
  5. 	auto m = 2; // #rows
  6. 	auto n = 3; // #cols
  7. 	// row-major vector
  8. 	auto x = std::vector<double>{1,2,3,4,5,6};
  9.  
  10. 	auto const colIndex = 1;
  11. 	auto const col = std::vector<double>{7,8};
  12. 	// insert column {7,8} into the 2nd position
  13. 	// =>{1,7,2,3,4,8,5,6}
  14.  
  15. 	// option 1: insert in-place
  16. 	// for(auto i = 0; i < col.size(); i++)
  17. 	// 	// +i b/c size increases by 1 each iteration
  18. 	// 	x.insert(begin(x) + colIndex + i * (n + 1), col[i]);
  19.  
  20. 	// option 2: temp vec and swap
  21. 	{
  22. 		auto tmp = std::vector<double>(m*(n+1));
  23.  
  24. 	    for(auto i = 0; i < m; i++)
  25.         {
  26.         	for(auto j = 0; j < colIndex; j++)
  27.                 tmp[j + i * (n + 1)] = x[j + i * n];
  28.  
  29.             tmp[colIndex + i * (n + 1)] = col[i];
  30.  
  31.             for(auto j = colIndex + 1; j < n + 1; j++)
  32.                 tmp[j + i * (n + 1)] = x[(j - 1) + i * n];
  33.         }
  34.  
  35.         std::swap(tmp, x);
  36. 	};
  37.  
  38. 	for(auto const& xi : x)
  39. 		std::wcout << xi << L" ";
  40.  
  41. 	return 0;
  42. }
Success #stdin #stdout 0s 15240KB
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https://ideone.com/iXrPfF
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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