I might be too tired right now. How can you find the distinct values in a container, or range?
I've looked through the algorithms library but I can't see anything standard. I could've sworn there was a standard algorithm to do it.
Aside from having a container B which I only add elements from container A which don't already appear...
**EDIT: would be good to get a count of each too.... like... SQL in C++11
Given an input vector v
, you can do something like
std::sort(begin(v), end(v)); // O(N log N) where N = v.size()
auto it = std::unique(begin(v), end(v)); // O(N)
Equivalently (well not really, since you need extra memory, the above method is in-place), you can copy them into and out of a std::set
:
std::set<T> s(begin(v), end(v)); // O(N log N);
auto it = std::copy(begin(s), end(s), begin(v)); // O(N);
Note that in both cases you need to actually erase the removed elements
v.erase(it, end(v)); // O(K), where K is the number of removed duplicates
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