1940번

1940

#include <iostream>
#include <vector>

using namespace std;

int n, m;
vector<int> v;
int answer = 0;

void getAnswer(int cnt, int index, int sum)
{
    if (cnt == 2)
    {
        if (sum == m)
        {
            answer++;
        }
        return;
    }
    for (int i = index + 1; i < n; i++)
    {
        getAnswer(cnt + 1, i, sum + v[i]);
    }
}

int main()
{

    cin >> n >> m;
    for (int i = 0; i < n; i++)
    {
        int number;
        cin >> number;
        v.push_back(number);
    }

    getAnswer(0, -1, 0);
    cout << answer;
}