求组合

	int[] arr = new int[] { 0, 1, 2, 3, 4, 5 };
	List<Integer> l = new ArrayList<>();
	int N = 4;

	public void combination(int i) {
		if (l.size() == N) {
			System.out.println(Arrays.toString(l.toArray(new Integer[0])));
			return;
		}
		for (; i < arr.length; i++) {
			l.add(arr[i]);
			combination(i + 1);
			l.remove(l.size() - 1);
		}
	}

	public static void main(String[] args) {
		WA wa = new WA();
		// wa.WholeArrangement(5);
		wa.combination(0);
	}