how to loop multimap only to get first key-value pairs for every key?

Question

For example if I have such mmap:

alice -> 30
bob -> 23
josh -> 20
josh -> 30
andy -> 40
andy -> 40

to get only this pairs:

alice -> 30
bob -> 23
josh -> 20
andy -> 40

Answer 1

This oughta do it as clean, and effective, as possible:

for(auto it = m.begin(); it != m.end(); it = m.upper_bound(it->first)) {
  std::cout << it->first << ":" << it->second << std::endl;
}

Answer 2

Here is a short answer, but not the most efficient

multimap<string, int> mm;
// Add stuff to multimap

// Map with only the first items from multimap
map<string,int> m;

for(auto iter = mm.rbegin(); iter != mm.rend(); ++iter){
   m[iter->first] = iter->second;
}

This works because we start from the end. Thus any duplicate keys in multimap will overwrite the previous key in map. Since we start from the end, we should have the first key