부분수열의 합

package 백준;

import java.util.Scanner;

public class 부분수열의합 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		N = sc.nextInt();
		S = sc.nextInt();
		arr = new int[N];
		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextInt();
		}

		for (int i = 0; i < N; i++) {
			sub_sum(i, 1, arr[i]);
		}
		System.out.println(count);
	}

	static int N;
	static int S;
	static int[] arr;
	static int count;

	static void sub_sum(int k, int cnt, int sum) {
		if (sum == S)
			count++;
		if (cnt == N)
			return;
		for (int i = k + 1; i < N; i++) {
			sub_sum(i, cnt + 1, sum + arr[i]);
		}
	}
}