Generate the Cartesian Product of 2 vectors In-Place?

Question

If I want to get the Cartesian Product of these two vectors:

vector final{\"a\",\"b\",\"c\"};
vector temp{         


        

Answer 1

Try the function cartesian:

#include 
#include 

using namespace std;

void cartesian(vector& f, vector &o) {
int oldfsize = f.size();
f.resize(oldfsize * o.size());
for (int i = o.size() - 1; i>=0; i--) {
  for (int j = 0; j < oldfsize; j++) {
     f[i*oldfsize + j] = f[j] + o[i];
  }
 }
}


int main() 
{
vector f{"a","b","c"};
vector temp{"1","2"};
cartesian(f, temp);
for (auto &s: f) {
  printf("%s\n", s.c_str());
 }
}