How can i erase duplicated elements from a multimap<int, std::pair<int, bool>>?

Question

I have a multimap with duplicates. When I finished the collection of the elements i would like to erase the dups.

Here is the container:

std::multimap<int, std::pair<int, bool>> container;

This following code is inside an iteration.(it is a simpler version of the original)

container.emplace(LeafId, std::make_pair(NodeId, isElectronic));

Is it good solution?

std::pair<int, std::pair<int, bool>> lastValue {-1 , {-1, -1}}; 
    for (auto it = container.cbegin(); it != container.cend();)
    {
        if (it->first == lastValue.first && it->second == lastValue.second)
        {
            it = container.erase(it);
        } else
        {
            lastValue = *it;
            ++it;
        }
    }

Answer 1

Is it good solution?

Unless you keep internal pair sorted inside multimap, no it is not a good solution as it would miss duplicates. If you can change data type then you can use:

std::map<int, std::vector<std::pair<int, bool>>>

instead of std::multimap and then for each element sort vector and remove duplicates using standard algorithms as described here Removing duplicates in a vector of strings

if you cannot I suggest to use additional std::set or std::unordered_set:

std::set<std::pair<int, bool>> tset;
int lastValue = 0;
for (auto it = container.cbegin(); it != container.cend();)
{
    if( it->first != lastValue ) {
        tset.clear();
        lastValue = it->first;
    }

    if( !tset.insert( it->second ).second )
        it = container.erase( it );
    else
        ++it;
}