This line
vector<boost::dynamic_bitset<>> v;
create an empty vector. Instead, you could request the filling of the default entries, all of which have the same value, so as usual
vector<int> v(N, 1);
to create a vector with Nall 1 entries that you could do
vector<boost::dynamic_bitset<>> v( N, boost::dynamic_bitset<>(3) ) ;
so that it contains N boost::dynamic_bitset<>with 3 bits.
If your vector contains enough elements, you should set v[i]to a different size
v[i] = boost::dynamic_bitset<>( 100 ) ;
, , - v.push_back(boost::dynamic_bitset<>(42)) .