How do i find median using c++ containers?

Question

I have created a program that asks for numbers until 0 is given. It then prints out the average, median, and descending, however, I don't know how to get the median. I have tried, and I get some type of result, but the program gives the wrong number as the median.

Input: 1 2 3 4 5 6 7 8 9 10 0 (Numbers are just an example)

Expected output:

Average : 5.5
Median : 5.5
Descending : 10 9 8 7 6 5 4 3 2 1

This is my attempt:

#include <iostream>
#include <vector>
#include<numeric>
#include "algorithm"

using namespace std;

int main() {
    vector<int> v;

    int n,i=0;
    double sum;

    cout << "Enter numbers(0 to stop inputting):"<<endl;
    cin>>n;

    while(n!=0){
        v.push_back(n);
        cin>>n;
    }

    for (const int& i : v) {
        sum = accumulate(v.begin(),v.end(),0);
    }

    double average = sum/v.size();
    cout<<"Average : "<<average<<endl;

    double Median = v[v.size()/2 -1];

    cout<<"Median : "<<Median<<endl;

    sort(v.begin(), v.end(), greater<int>());
    cout << "Descending : ";
    for (auto i : v)
        cout << i << " ";
    cout<<endl;
}

[Hint] The median is either the middle element when you have an odd number of elements or the average of the two middle elements if you have an even number of elements. — NathanOliver, Dec 09 '22 at 13:29
Why are you doing `sum = accumulate(v.begin(),v.end(),0);` in a loop? — Some programmer dude, Dec 09 '22 at 13:34
You might want to have a look at std::nth_element() for the median. — m2j, Dec 09 '22 at 13:35
@NathanOliver Ah true, I think my eye slipped to the previous line and I read it as `int sum;`. — Konrad Rudolph, Dec 09 '22 at 13:49

Wyrzutek · Answer 1 · 2022-12-09T13:55:23.810

#include <iostream>
#include <vector>
#include<numeric>
#include "algorithm"

using namespace std;

int main() {
    vector<int> v;

    int n,i=0;

    cout << "Enter numbers(0 to stop inputting):"<<endl;
    cin>>n;

    while(n!=0){
        v.push_back(n);
        cin>>n;
    }

    // no for!
    double sum = accumulate(v.begin(),v.end(),0);

    double average = sum/v.size();

    // sort BEFORE getting the middle element!
    sort(v.begin(), v.end(), greater<int>());

    double Median =
        v.empty() ? 0.0 :
        v.size() % 2 == 0 ? (v[v.size()/2 -1] + v[v.size()/2]) / 2.0 : // even count
        v[v.size()/2]; // odd count

    cout<<"Average : "<<average<<endl;
    cout<<"Median : "<<Median<<endl;
    cout << "Descending : ";
    for (auto i : v)
        cout << i << " ";
    cout<<endl;
}

How do i find median using c++ containers?

1 Answers1