Write a C++ program to find the number of pairs of integers in a given array of integers whose sum is equal to a specified number

#include <iostream>
using namespace std;
int main()
{
    int array1[] = {1, 5, 7, 5, 8, 9, 11, 12};
    int s1 = sizeof(array1)/sizeof(array1[0]);

    cout << "Original array: ";
    
    for (int i=0; i < s1; i++) 
    cout << array1[i] <<" ";
    
    int i, sum = 12, ctr = 0;
    cout <<"\nArray pairs whose sum equal to 12: ";
    
    for (int i=0; i<s1; i++)
        for (int j=i+1; j<s1; j++)
            if (array1[i]+array1[j] == sum)
              {
                cout << "\n" << array1[i] << "," << array1[j];
                ctr++;
              }
 
    cout <<"\nNumber of pairs whose sum equal to 12: ";
    cout << ctr;
    
    return 0; 
}