two_sum.cpp

#include <iostream>
#include <vector>
#include <unordered_set>
using namespace std;
void two_sum(int array[], int sum)
{
    unordered_set<int> us;
    vector<int> v (array, array+7);
    for (int i = 0; i < v.size(); i++) {
        if (us.find(sum - array[i]) == us.end()) {
            us.insert(array[i]);
        } else {
            cout << sum - array[i] << " and " << array[i] << endl;
        }
    }
    return;
}

int main(int argc, char *argv[]) {
    int array[] = {1, 4, 5, 7, 11, 16, 17};
    int sum = 15;
    two_sum(array, sum);
    return 0;
}