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Prefer unordered_set over vector


Prefer unordered_set over vector

By : BMG Vlogs
Date : November 22 2020, 09:00 AM
hope this fix your issue
Is it safe to say that if I don't want duplicates in my container, and I don't care about element position as I only want to iterate through the container, then I should use an unordered_set instead of vector?
code :


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Is std::unordered_set contiguous (like std::vector)?

Is std::unordered_set contiguous (like std::vector)?


By : Shirish Surti
Date : March 29 2020, 07:55 AM
it should still fix some issue I'm storing pointers in std::unordered_set, because I don't want any duplicate (I delete the pointers in the collection, so if there is a duplicate I will attempt to delete an already deleted pointer). I loop heavily through these sets, and since I know std::vector is the fastest container for looping (contiguous memory), I wondered if std::unordered_set does the same. ,
Is std::unordered_set contiguous ?
std::vector faster than std::unordered_set?

std::vector faster than std::unordered_set?


By : Eddy Irish
Date : March 29 2020, 07:55 AM
like below fixes the issue There are two possibilities I can think of:
You have a small enough number of data elements that a linear search is faster than a hash-plus compare lookup. You're using the same contains function to find an element in the unordered_set, instead of using the member function find.
set vs unordered_set vs sorted vector

set vs unordered_set vs sorted vector


By : user2618129
Date : March 29 2020, 07:55 AM
help you fix your problem I started to wonder what is the exact performance difference between set/unordered_set/sorted vector. ,
Do statements sounds right?
How to use std::unordered_set to a vector<vector<int>> to remove duplicates

How to use std::unordered_set to a vector<vector<int>> to remove duplicates


By : Satya Nugraha
Date : March 29 2020, 07:55 AM
help you fix your problem You are trying to insert something into your std::unordered_set something which is not an int.
It is not clear to me what your "intervals" are, or what you are doing when sorting. Perhaps this is some use?
code :
#include <iostream>
#include <vector>
#include <set>

int main()
{
    std::vector<std::vector<int> > sharedAnswersVec = {
        {1,2,3,5,7,11,13,17,19,23,29},
        {2,5,11,17,23,29}
    };

    std::set<int> unique_primes;
    for ( const auto& v : sharedAnswersVec )
    {
        for ( auto i : v )
        {
            unique_primes.insert(i);
        }
    }

    for ( auto i : unique_primes )
    {
        std::cout << i << std::endl;
    }
    return 0;
}
cpp Is there a reason to prefer vector<class_type*> to vector<void*>?

cpp Is there a reason to prefer vector<class_type*> to vector<void*>?


By : John
Date : March 29 2020, 07:55 AM
Hope this helps Using void * should be avoided whenever possible.
This is for two reasons:
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