How to keep only duplicates efficiently?
- by Marc Eaddy
Given an STL vector, I'd like an algorithm that outputs only the duplicates in sorted order, e.g.,
INPUT : { 4, 4, 1, 2, 3, 2, 3 }
OUTPUT: { 2, 3, 4 }
The algorithm is trivial, but the goal is to make it as efficient as std::unique(). My naive implementation modifies the container in-place:
My naive implementation:
void…
