Remove duplicate element from vector of vectors c++ -

i'm trying remove duplicated item bigger vector
ex:

6 11   7 8 6 16 17 

i should get:

6 11   7 8 16 17 

what have:

vector<vector<int>>b; vector<vector<int>>::iterator b_list; vector<vector<int>>::iterator b_it; vector<int>::iterator b_list_it; vector<int>::iterator b_it_it; (b_list = b.begin(); b_list != b.end()-1; ++b_list) {     (b_it = b_list+1; b_it != b.end(); ++b_it)     {          (int = 0; < (*b_list).size(); ++i)         {             (int j = 0; j < (*b_it).size(); ++j)             {                 if ((*b_list)[i] == (*b_it)[j])                 {                     if ((*b_list).size() > (*b_it).size())                         {                                (*b_list).erase((*b_list).begin());                         }                         if ((*b_list).size() < (*b_it).size())                         {                             (*b_it).erase((*b_it).begin());                         }                 }              }          }      } } 

in case erase() doesn't remove anything. why so? , used instead of it?

thank you!

since op has 2 dimensional vector. not sure if op wants data in sorted (unique can used in case) taking assumption not sorted set used tracker . keeps track of unique values . if (ret.second!=false) fogrow.push_back(s);a copy vector used every time unique values there pushed in

// //  main.cpp //  ranged // //  created hariom singh on 9/9/17. //  copyright © 2017 hariom singh. rights reserved. //  #include <iostream> #include <string> #include <vector> #include <set>  int main() {     std::vector<std::vector<int> >  val {{6,11},{7,8},{6,16,17}};     std::vector<std::vector<int> >  uniquevalcopy;     std::set<int> tracker;     ( const auto &row : val )     {         std::vector <int> fogrow;         ( const auto &s : row )         {             std::cout << s << ' ';             auto ret = tracker.insert(s);             if (ret.second!=false)             fogrow.push_back(s);          }         uniquevalcopy.push_back(fogrow);         std::cout << std::endl;     }      std::cout<<"after removal"<<"\n";     ( const auto &row : uniquevalcopy )     {         ( const auto &s : row )         {             std::cout << s << ' ';          }         std::cout << std::endl;     }     return 0; } 

output

6 11  7 8  6 16 17  after removal 6 11  7 8  16 17  program ended exit code: 0