Flip map key-value pair

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后悔当初 2021-01-11 17:10

I have a map. I want to flip the key-value so that it not becomes map. So basically the value of the first map becomes the key of the second map. How do i do this?

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旧时难觅i (楼主)

2021-01-11 17:33

#include
#include
#include

using namespace std;

template
pair flip_pair(const pair &p)
{
    return pair(p.second, p.first);
}

template
map flip_map(const map &src)
{
    map dst;
    transform(src.begin(), src.end(), inserter(dst, dst.begin()), 
                   flip_pair);
    return dst;
}

int main(void)
{
  std::map src;

  src['a'] = 10;
  src['b'] = 20;
  src['c'] = 160;
  src['d'] = 110;
  src['e'] = 0;

  std::map dst = flip_map(src);

  map::iterator it;
  for(it=dst.begin(); it!=dst.end(); it++) {
    cout << it->first << " : " << it->second << endl;
  }
}

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