// Count all possible pairs of array elements with sum equal to a given number / O(n)

// given number = 5

// array = [ 1, -4, 0, 9, 8, -3, 7, 5, 9];

// Expected result: 4

​

using System;

using System.Collections.Generic;

using System.Linq;

using System.Collections;

​

class Solution

{

    static void Main(String[] args)

    {

        int number = 5;

        int[] array = [ 1, -4, 0, 8, 9, -3, 7, 5, 9];

​

        DoMagic(array, number);

​

        number = 2;

        array = [ 1, 1, 1, 1];

​

        DoMagic(array, number);

    }

    public static void DoMagic(int[] array, int number)

    {

    }

}

​