So I'm trying to figure out a way to do the exercise 3.20 in the c++ primer book

I have to create a program that reads input into a vector then use that data to create 2 outputs.

• one is the sum of each adjacent number
• one is the sum of the first and last number moving inwards ( as in the 2nd and 2nd last, 3rd and 3rd last etc)

I've created the following code, but it feels off somehow. Can I simplify/clean up this stuff a bit? (not going to far)

Thanks for your input!

#include <vector>
#include <string>
#include <iostream>
#include <cctype>

using std::cin; using std::cout; using std::endl; using std::vector; using std::string;

int main()
{
    vector<int> nv;
    int n;

    while (cin >> n)
    {
        nv.push_back(n);
    }

    int cnt = 0;
    int output = 0;
    int oldnum = 0;
    
    //output sum of adjacent
    for (int cn : nv)
    {
        output += cn; 
        output += oldnum;
        ++cnt;

        if (cnt == 2)
        {
            cout << output << " ";
            cnt = 1;
            output = 0;
            oldnum = cn;
        }

    }
    cout << endl;

    //output sum of first and last
    int trigger = 1;
    for (decltype(nv.size()) i = 0; i < (nv.size()/2); ++i)
    {
        cout << (nv[trigger - 1]) + (nv[nv.size() - (1 * trigger)]) << " ";
        ++trigger;
    }
    return 0;
}

I'm trying to figure out a way to do the exercise 3.20 in the C++ primer book

I have to create a program that reads input into a vector then use that data to create 2 outputs:

• one is the sum of each adjacent number
• one is the sum of the first and last number moving inwards (as in the 2^nd and 2^nd last, 3^rd and 3^rd last etc)

I've created the following code, but it feels off somehow. Can I simplify/clean up this stuff a bit?

#include <vector>
#include <string>
#include <iostream>
#include <cctype>

using std::cin; using std::cout; using std::endl; using std::vector; using std::string;

int main()
{
    vector<int> nv;
    int n;

    while (cin >> n)
    {
        nv.push_back(n);
    }

    int cnt = 0;
    int output = 0;
    int oldnum = 0;
    
    //output sum of adjacent
    for (int cn : nv)
    {
        output += cn; 
        output += oldnum;
        ++cnt;

        if (cnt == 2)
        {
            cout << output << " ";
            cnt = 1;
            output = 0;
            oldnum = cn;
        }

    }
    cout << endl;

    //output sum of first and last
    int trigger = 1;
    for (decltype(nv.size()) i = 0; i < (nv.size()/2); ++i)
    {
        cout << (nv[trigger - 1]) + (nv[nv.size() - (1 * trigger)]) << " ";
        ++trigger;
    }
    return 0;
}