Most efficient way of erasing/deleting multiple std::vector elements while retaining original order?

Question

i have a std::vector and a second container holding iterators or indexes (no keys, i want constant access to the element) to this vector for del

Answer 1

How about looping through the vector, and for each element that needs to be removed, copy the next element that doesn't need to be removed in to that position. Then when you get to the end, truncate it.

int last = 0;
for(int i=0; i= vec.size()) break;

   vec[last] = vec[i];   
}

vec.resize(last);