pair-sum.cpp

#include <iostream>
using namespace std;

int pairSum(int *input, int size, int x)
{
    int count = 0;

    for (int i = 0; i < size; i++)
    {
        for (
            int j = i + 1;
            j < size; j++)
        {
            if (input[i] + input[j] == x)
            {
                count++;
            }
        }
    }

    return count;
}

int main()
{
    int t;
    cin >> t;

    while (t--)
    {
        int size;
        int x;

        cin >> size;
        int *input = new int[size];

        for (int i = 0; i < size; i++)
        {
            cin >> input[i];
        }

        cin >> x;

        cout << pairSum(input, size, x) << endl;

        delete[] input;
    }

    return 0;
}