pairsequalsum.cpp

// How do you find all pairs of an integer array whose sum is equal to a given number?

#include <iostream>
#include <array>

int desired_sum = 10;
std::array<int, 10> arr = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

int main ()
{
    int i, j;   
    for ( i = 0; i < arr.size(); ++i)
        for ( j = i; j < arr.size(); ++j )
            if ( arr[i] + arr[j] == desired_sum )
                std::cout << i << " " << j << std::endl;
}