C++ Unable to get the correct answer for median value

Question

Ok so I created a program that takes in a vector and calculates the median. Although im getting the correct median value for odd number, im not getting the same for even. here is my code:

#include <iostream>
#include <vector>
using namespace std;

int main()
{
    bool check;
    cout<<"Hello World";
    vector<double> vec;

    vec.push_back(2);
    vec.push_back(6);
    vec.push_back(8);
    vec.push_back(62);

    double median;
    if(check==vec.size()%2)
    {
        median=(vec[vec.size() / 2 - 1] + vec[vec.size() / 2]) / 2;
    }
    else{
         median=vec[(vec.size() / 2.0)];
    }
    cout<<median;
    return 0;
}

so when i checked online, the correct answer should be 7 but I get 8.. And this happens only for the even number calculation.. what am i doing wrong i dont get it

Answer 1

I rewrote your code and cleaned up some unnecessary variable. I per-calculated the array size n and the midpoint centerElement. You do not want to repeatedly do this calculation specially in scenarios where you have a very large array.

I also removed the boolean variable check, which is completely unnecessary. You can find simply compare the output of modulus operation by comparing it with 0

    #include <iostream>
    #include <vector>
    using namespace std;

    int main()

{
    vector<double> vec;    
    vec.push_back(2);
    vec.push_back(6);
    vec.push_back(8);
    vec.push_back(100);
    auto n = vec.size();
    auto centerElement = n/2;

    double median;
    if(n%2 == 0)
    {
        median=(vec[centerElement - 1] + vec[centerElement]) / 2;
    }
    else{
         median=vec[(centerElement)];
    }
    cout<<median;
    return 0;
}