BOJ 1182번 부분수열의 합

import java.util.Scanner;

public class BOJ_1182 {

    static int[] num;

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int s = sc.nextInt();

        num = new int[n];
        for (int i = 0; i < n; i++) {
            num[i] = sc.nextInt();
        }

        int answer = 0;

        for (int i = 1; i < (1 << n); i++) {
            int sum = 0;
            for (int k = 0; k < n; k++) {
                if ((i & (1 << k)) != 0)
                    sum += num[k];
            }

            if(sum == s)
                answer++;
        }
        System.out.println(answer);

    }

}