Remove Duplicate Entries in a C++ Vector

Question

Just want to remove duplicates. Pool is vector> but I seem to miss some elements at the start of the vector somehow. Can anyone verify

Answer 1

This is a very common issue.

Because after you erase an element the position j pointed will skip one element due to the j++ on the for loop. the easiest solution to solve the problem based on your code is to add j-- after generation.erase(iter):

  generation.erase(iter);
  j--;

Answer 2

If you don't mind sorting the vector, then you can use std::unique. That would be O(Nlog(N))

#include <iostream>
#include <algorithm>
#include <vector>

int main() 
{
    std::vector<int> v{1,2,3,1,2,3,3,4,5,4,5,6,7};
    std::sort(v.begin(), v.end()); 
    auto last = std::unique(v.begin(), v.end());
    v.erase(last, v.end());
    for (const auto& i : v)
      std::cout << i << " ";
    std::cout << "\n";
}