c++ - std::map using large amounts of memory -

c++ - std::map using large amounts of memory -

i have array of bins:

vector<vector<int> > bins

the programme calculates big amount of object of type term , corresponding integer. every bin corresponds term object, , ints need end in bins. doing this:

map<term, int> helpermap; int binnumber=0; while(/*some condition*/) { term temp; int tempint; //do calculation find temp & tempint if (helpermap.find(temp)==helpermap.end()) { vector<int> newbin; newbin.push_back(tempint); bins.push_back(newbin); helpermap[temp] = binnumber; binnumber++; } else { bins[helpermap.find(temp)->second].push_back(tempint); } }

the problem map (which don't need anymore farther on) requires much more memory bin structure, , putting serious constraints on program. there more efficient way this?

i in 2 steps. spin through loop once, calculate how many bins you're going need, , phone call bins.resize(numberyouwillneed) - spin through 1 time again , need bins[x].push_back(tempint); - result in far fewer memory allocations too, making faster. depending on whether calculations expensive , whether can them once.

however, can't see helpermap beingness enormously bigger bins - sure problem?

c++ std