More elegant way to check for duplicates in C++ array?

Question

I wrote this code in C++ as part of a uni task where I need to ensure that there are no duplicates within an array:

// Check for duplicate numbers in user in         


        

Answer 1

Indeed, the fastest and as far I can see most elegant method is as advised above:

std::vector tUserNumbers;
// ...
std::set tSet(tUserNumbers.begin(), tUserNumbers.end());
std::vector(tSet.begin(), tSet.end()).swap(tUserNumbers);

It is O(n log n). This however does not make it, if the ordering of the numbers in the input array needs to be kept... In this case I did:

    std::set tTmp;
    std::vector::iterator tNewEnd = 
        std::remove_if(tUserNumbers.begin(), tUserNumbers.end(), 
        [&tTmp] (int pNumber) -> bool {
            return (!tTmp.insert(pNumber).second);
    });
    tUserNumbers.erase(tNewEnd, tUserNumbers.end());

which is still O(n log n) and keeps the original ordering of elements in tUserNumbers.

Cheers,

Paul